Fall and Rise: The Story of 9/11: A gripping biography of triumph over tragedy

by Mitchell Zuckoff

“If you didn’t go through it, there are no words that can adequately describe it; if you were there, then no words are necessary.”

the February 1998 fatwa asserted that three primary offenses justified a declaration of global war: (1) the presence of American military forces on the holiest lands of Islam, the Arabian Peninsula; (2) the U.S.-led war in Iraq; and (3) the United States’ support of Israel, in particular its control of Jerusalem. “All of these crimes and sins committed by the Americans,” the statement said, “are a clear declaration of war on Allah, his messenger, and Muslims.” In response, bin Laden and his cohort issued a command: “The ruling to kill the Americans and their allies—civilians and military—is an individual duty for every Muslim who can do it in any country in which it is possible to do it… .

A Gallup poll taken on September 10, 2001, found that fewer than 1 percent of Americans considered terrorism to be the nation’s No. 1 concern. But they didn’t know that a countdown had already begun. Nineteen bin Laden devotees, radicalized young Arab men living in the United States, awoke on September 11, 2001, determined to fulfill the fatwa. In twenty-four hours, the poll results would change, along with everything else.

Nationally, NORAD and its divisions could immediately call upon fourteen fighter jets, two each at seven bases around the country. Those fighters remained perpetually “on alert,” armed and fueled, pilots ready. The military had many more fighter jets spread among U.S. bases, but time would be needed to round up pilots and load fuel and weapons, and time would be an unaffordable luxury if America came under attack. During the decade since the fall of the Soviet Union, America’s leaders had behaved as though the airborne threat had nearly disappeared. At fourteen, the number of on-alert fighters nationwide marked a sharp drop since the height of the Cold War, when twenty-two military sites, with scores of fighter jets, were always ready to defend against a ballistic missile attack or any other threat to North America. In fact, by the summer of 2001, the number of on-alert fighter jet sites throughout the United States had been ordered to be cut from fourteen to only four, to save money, though that order had yet to be carried out.

Nasypany and other NEADS officers regularly put their crews through elaborate exercises. They had one planned for September 11, with the impressive name Vigilant Guardian. The drill focused on a simulated attack by Russian bombers, with elaborate secondary scenarios including a mock hijacking by militants determined to force a passenger jet to land on a Caribbean island. Nasypany and some colleagues wanted the exercise to include a plot by terrorists to fly a cargo plane into the United Nations building in New York City, but a military intelligence officer had nixed that idea as too far-fetched to be useful.

Known to al-Qaeda as the Planes Operation, the plot was reportedly the brainchild of a longtime terrorist named Khalid Sheikh Mohammed, who’d met bin Laden in the 1980s. Mohammed admired the murderous ambitions of his nephew Ramzi Yousef, who carried out the 1993 World Trade Center bombing. After Yousef’s 1995 arrest in Pakistan, as the terrorist was flown by helicopter over Manhattan, a senior FBI agent lifted Yousef’s blindfold and pointed out the World Trade Center’s Twin Towers, aglow in the dark. The agent taunted his prisoner: “Look down there. They’re still standing.” Yousef replied: “They wouldn’t be if I had enough money and explosives.”

their flight training stalled after they told an instructor they wanted to learn how to fly a plane but showed no interest in takeoffs or landings.

Embrace the will to die and renew allegiance. -Shave the extra body hair and wear cologne. -Pray. Familiarize yourself with the plan well from every aspect, and anticipate the reaction and resistance from the enemy. Read the Al-Tawbah [Repentance], the Anfal chapters [in the Quran], and reflect on their meaning and what Allah has prepared for the believers and the martyrs in Paradise. Near the end of the first section, it offered this direction: 13. Examine your weapon before departure, and it was said before the departure, “Each of you must sharpen his blade and go out and wound his sacrifice.” Among the nineteen men with plans to wreak havoc in the next twenty-four hours, at least two others, one in New Jersey and the other outside Washington, had copies of the same letter.

Before he left, Michael scanned down the aisle, almost out of habit, to see if the attendants had closed all the overhead bins. As he looked through the business section, Michael locked eyes with the passenger in seat 8D. A chill passed through him, a queasy gut feeling he couldn’t quite place and couldn’t shake. Something about Mohamed Atta’s brooding look seemed wrong. But the flight was already behind schedule, and Michael wouldn’t challenge a passenger simply for glaring at him. He turned and stepped off Flight 11, and a gate agent closed the door behind him.

But all that training revolved around certain narrow expectations about how hijackings transpired, based on decades of hard-earned experience. Above all, those expectations relied on an assumption that one or both of the pilots, John Ogonowski and Tom McGuinness, would remain at the controls. The idea that hijackers might incapacitate or eliminate the pilots and fly a Boeing 767 themselves didn’t register in the minds of Boston Center controllers. To them, the old rules still applied.

The concept of more than one hijacking simultaneously and in coordination wasn’t on anyone’s radar, literally or figuratively. Years had passed since the last hijacking of a U.S. air carrier, and coordinated multiple hijackings had never happened in the United States. Almost no one in the FAA, the airlines, or the military had dealt with such a scenario or considered it a likely threat. The last organized multiple hijackings anywhere in the world had occurred more than three decades earlier, in September 1970, when Palestinian militants demanding the release of prisoners in Israel seized five passenger jets bound from European cities to New York and London.

All nine flight attendants had keys to the cockpit, but it’s not clear how the hijackers gained entry—Atta and his crew might have attacked Karen and Bobbi to steal their keys, or the hijackers might have gotten into the cockpit another way. When the plane dipped and pitched erratically, Betty suspected that a hijacker was already in control. She said she thought they had “jammed the way up there.” In fact, the cockpit doors were relatively flimsy and weren’t strong enough to prevent forced entry. Another possibility was that the hijackers stabbed the first-class flight attendants to induce the pilots to open the cockpit door. Or maybe it was even simpler: In September 2001, one key opened the cockpit doors of all Boeing planes. Maybe the hijackers brought a key on board with them.

At the American Airlines center in Fort Worth, Nydia Gonzalez begged for information: “What’s going on, Betty? … Betty, talk to me… . Betty, are you there? … Betty?” Betty didn’t answer. Nydia turned to her colleagues: “Do you think we lost her? Okay, so we’ll like—we’ll stay open.” Then Nydia Gonzalez added an unintentionally haunting coda to Betty Ong’s bravery: “We—I think we might have lost her.”

Michael tried his best to calm Amy. He told her to look out the window and tell him what she saw. “We are flying low,” she said. Amy told Michael she saw water and buildings. “We are flying very, very low. We are flying way too low!” Amy paused. Powerless on the other end of the phone, Amy’s colleague and friend Michael Woodward waited, every second stretching into a lifetime. Less than an hour earlier, he’d stood inside the plane, locked eyes with Mohamed Atta, and waved goodbye to his friends. Michael heard Amy’s last words, before the call dissolved into static: “Oh my God!—We are way too low!”

UNDER THE COMMAND and control of fanatics bent on murder and determined to commit suicide, American Airlines Flight 11 had been transformed from a passenger jet into a guided missile.

The Boeing 767 that was American Airlines Flight 11 completed an unapproved, L-shaped path through bright blue skies that covered roughly three hundred miles from Boston, west to Albany, then south over the streets of Manhattan. At the last millisecond of its trip, at a speed estimated at 440 miles per hour, the silver plane’s nose touched the glass and steel of the north face of the 96th floor of the North Tower of the World Trade Center. TJX planning manager Tara Creamer’s instructions to her husband, John, on how to care for their children would need to last a lifetime. Cambodian farmers who relied on John Ogonowski would have to find a new teacher and patron. His wife and daughters would be set adrift without their anchor. Amy Sweeney’s children would have to get to school, and through life, without her. Betty Ong’s elderly friends would need new rides to doctors’ appointments. Her sister Cathie would never again hear her say “I love you lots.” Robert Norton’s stepson would have to get married without him. Daniel Lee’s soon-to-be-born daughter would spend her entire life without him. Daniel Lewin’s family and his company would have to forge new paths without his genius or his guidance. Someone else would have to find a health aide for Cora Hidalgo Holland’s mother. Susan MacKay’s air traffic controller husband, Doug, who planned to have John Ogonowski say hi for him, would have to live with the knowledge that Susan passed through airspace over the Hudson River Valley t...

Nothing was safe in their path. A New York Center controller watched as the United plane turned toward a Delta 737 flying southwest at 28,000 feet. “Traffic two o’clock! Ten miles,” the controller warned the Delta pilots. “I think he’s been hijacked. I don’t know his intentions. Take any evasive action necessary.” The Delta flight ducked away from United 175, but soon after, the hijacked plane put itself on a collision course with a US Airways flight. An alarm sounded in the US Airways cockpit, and the pilots dived to avoid a midair crash.

Brian’s call, at shortly before 8:59 a.m., went to their answering machine. He spoke in a calm, serious tone, and his message echoed what he’d told Julie weeks earlier about how he wanted her to “celebrate life” if anything happened to him: “Jules, this is Brian. Listen, I’m on an airplane that’s been hijacked. If things don’t go well, and it’s not looking good, I just want you to know I absolutely love you. I want you to do good, go have a good time. Same to my parents and everybody. And I just totally love you, and [anticipating heaven or an afterlife] I’ll see you when you get there. ’Bye, babe. Hope I’ll call you.” Brian hung up. Then he punched in the numbers for another telephone call. AS LOUISE SWEENEY prepared to leave home to run errands, the phone rang. She picked up to hear her son’s voice: “Mom, It’s Brian. I’m on a hijacked plane and it doesn’t look good. I called to say I love you and I love my family.” Brian told his mother that he didn’t know who the hijackers were. Calling from the rear of the plane, he said he thought they might come back, so he might have to hang up quickly. He told her he believed that they might be flying somewhere over Ohio. Brian said he and other passengers might storm the cockpit. Louise knew her son, and she recognized how he sounded when he became “pissed off.” He had that tone. Before ending the call, Brian told her, “Remember Crossing Over. Don’t forget Crossing Over.” Louise remembered, and she wouldn’t forget. As Flight 175 s...

United Airlines Flight 175 flew low and fast, banking toward the southern twin of the burning North Tower of the World Trade Center. Flight controllers, airline officials, government and military experts, and everyone else would need to accept a new script for hijackings, one that featured a multipronged murder-suicide plot designed to maximize civilian casualties and terrorize survivors through the destruction of physical and symbolic pillars of America’s power.

The evidence flashed on the air traffic controllers’ radar screens. “No!” a New York controller shouted. “He’s not going to land. He’s going in!”

FROM THE BACK of the plane, with his wife and daughter pressed against him, Peter Hanson spoke his final words to his father: “Oh my God… . Oh my God, oh...

At 9:03:11 a.m., Lee and Eunice Hanson, Louise Sweeney, and millions of others became witnesses to murder. They watched live on television as United Flight 175, traveling between 540 and 587 miles per hour, slammed on an angle into the 77th through 85th floors of the South Tower of the World Trade Center. A bright orange fireball exploded. The building rocked and belched smoke, glass, steel, and debris. The plane and everyone inside it disappeared forever.

Unlike their associates aboard the other two flights, three of the al-Qaeda members on American Flight 77 nearly had their plans foiled by airport security. At 7:18 a.m., Majed Moqed and Khalid al-Mihdhar set off alarms when they walked through a Dulles Airport metal detector. Security workers sent them to a second metal detector. Mihdhar passed, but Moqed failed again. A private security officer hired by a contractor for United Airlines scanned Moqed with a metal detection wand and sent him on his way. Neither was patted down. Almost twenty minutes later, Nawaf al-Hazmi set off alarms at both metal detectors at the same security checkpoint. Two weeks earlier, he’d purchased Leatherman multitool knives, and a security video showed that he had an unidentified item clipped onto his rear pants pocket. A security officer hand-wanded Hazmi and swiped his shoulder bag with an explosive trace detector. No one patted him down, and he walked on toward Flight 77 with his brother, Salem al-Hazmi.

Next to him, in 12B, was Khalid al-Mihdhar, slim and dark-haired, a man who U.S. intelligence officials had known for several years was a member of al-Qaeda, yet who traveled under his real name.

Nash looked down from his cramped cockpit at the burning towers. Thick black smoke spiraled upward to space. Nash thought: “That was the start of World War III.” If Nash was correct, the next battle had already begun, and the battlefield would be Washington, D.C.

THROUGHOUT THE MORNING, as minutes ticked past and the terror swelled, only the hijackers and their al-Qaeda bosses knew how many planes they intended to seize. It could be two, ten, or more. But from the terrorists’ perspective, the first hour of their attack went like clockwork: so far, they’d hijacked three planes, two of which had struck their targets in New York and the third was under their control, coursing toward Washington, D.C. Those results were the fruits of a poisoned tree. After months of research and reconnaissance led by Mohamed Atta, the hijackers had guessed correctly about how their victims in the air and their enemies on the ground would and wouldn’t react to a hostile airborne takeover. During the first three hijackings, fifteen terrorists had used planning, training, subterfuge, and deadly violence to exploit preconceived notions and gaping weaknesses they’d identified in U.S. airline security, all in service to Osama bin Laden’s 1998 declaration of war against the United States and its people.

The hijackers on American Flight 11, United Flight 175, and American Flight 77 had boarded without incident, despite their apparent possession of short-bladed knives, not to mention previous travels and associations that should have been flaming red flags. They’d swiftly gained access to cockpits and replaced pilots with men who’d trained to fly jets expressly for the purpose of becoming martyrs. “Muscle” hijackers spread fear by attacking several crew members and passengers. They herded the rest to each plane’s rear section to keep them out of the way. Claims about bombs, whether true or (more likely) false, confused and frightened passengers and crew members into obedience, perhaps with the exception of former Israeli commando Danny Lewin on Flight 11, whose throat was apparently slashed by the hijacker who sat behind him. Announcements from terrorist pilots in the cockpits, even if not all were heard by passengers and crew members, were lies designed to trick their hostages into believing that these were “ordinary” hijackings, with political or monetary goals, and that no one else would be hurt if the terrorists were allowed to fly to their chosen destination and if authorities on the ground satisfied their demands.

During the first three flights, the tightly choreographed strategy worked. And one of the most important elements was timing. The plan to use the hijacked planes as weapons of mass destruction depended on the hijackers’ ability to commandeer and maintain control of fuel-heavy transcontinental flights that took off within a few minutes of one another. That narrow window maximized the element of surprise, which the hijackers understood or hoped would lead to a chaotic response, too late to stop them from reaching their intended targets. Conversely, delays would increase the chance that they’d be stopped on the ground by a shutdown of air traffic, confronted in the air by fighter jets, or challenged on board by passengers and crew members who might discover that other hijackings hadn’t ended with safe landings and the release of innocents. Just as Atta intended, American Flight 11 and United Flight 175 took off from Boston’s Logan Airport only fifteen minutes apart, at 7:59 a.m. and 8:14 a.m. respectively, each fourteen minutes after its scheduled departure time. American Flight 77 left Washington’s Dulles Airport at 8:20 a.m., ten minutes after its scheduled departure. In fact, al...

If the group of terrorists on United Flight 93 tried to follow the pattern of their collaborators aboard Flights 11, 175, and 77, they were clearly one hijacker short. A Saudi man who authorities later suspected was supposed to have been the twentieth hijacker had landed a month earlier at Florida’s Orlando International Airport, arriving on a flight from London. He landed with no return ticket or hotel reservations, carried $2,800 in cash and no credit cards, spoke no English, and claimed he didn’t know his next destination after he intended to spend six days in the United States. He grew angry when questioned by an alert immigrations inspector named José E. Melendez-Perez, who suspected that the man was trying to immigrate illegally. Melendez-Perez thought the Saudi fit the profile of a “hit man.” He consulted with supervisors, then forced the man onto a flight to Dubai, via London. Waiting in vain that day at the Orlando airport was Mohamed Atta.

chime, and

EVEN AFTER TWO HIJACKED JETS STRUCK THE WORLD TRADE CENTER, even as concern mounted among Indianapolis Center controllers about strange behavior by American Airlines Flight 77, no one from the FAA informed the U.S. military that a plane that took off from Dulles Airport had stopped communicating by radio and had disappeared from radar screens after someone turned off its cockpit transponder.

BY 9:25 A.M., even as American Flight 77 remained missing and a mystery, one top FAA official grasped the severity and growing scope of the crisis. At the agency’s operations center in Herndon, Virginia, FAA national operations manager Ben Sliney knew about the North Tower crash and had seen United Flight 175 hit the South Tower on CNN some twenty minutes earlier. He worried about the disappearance of Flight 77 and feared that more hijackings might be under way. Sliney also had heard about Mohamed Atta’s “We have some planes” remark. He felt haunted by the question of how high the hijacking total might eventually reach. He couldn’t undo what already happened, but Sliney hoped that he might help prevent the next attack. Fifty-five years old, with a shock of white hair, an Air Force veteran and a lawyer by training, Sliney concluded that he had both the authority and the responsibility to take drastic action. Accordingly, he declared a “nationwide ground stop,” the first order of its kind in U.S. aviation history, which prevented all commercial and private aircraft from taking off anywhere in the United States. Making Sliney’s order even more remarkable, he had only recently returned to the FAA after several years in a private law practice. The morning of September 11 was Sliney’s first shift on his first day in his new job as the FAA’s National Operations Manager, boss of the agency’s command center.

AT 9:32 A.M., air traffic controllers at Dulles airport saw a green dot on their radar screens that no one expected, traveling eastbound at the surprisingly fast speed of about 500 miles per hour. Among those who noticed the unidentified aircraft was Danielle O’Brien, the air traffic controller who for some reason had wished Flight 77’s pilots “good luck” when she handed them off an hour earlier. From its speed and how it turned and slashed across the sky, she and other controllers initially thought the object on their radar was a nimble military jet. O’Brien slid to her left and pointed it out to the controller next to her, her fiancé, Tom Howell, who recognized it as a threat. “Oh my God,” Howell said. He yelled to the room: “We’ve got a target headed right for the White House!”

Just when they were needed most, when every second and every movement counted, the two Langley F-16s were about one hundred fifty miles away—the result of an incorrect flight plan generated by misunderstandings, a mistake on coordinates by a military air traffic controller, and an overall lack of information, communication, and coordination. Still, with the Twin Towers burning and the capital under threat from an unknown aircraft, Nasypany wouldn’t quit. He wanted the fighters to fly supersonic, faster than the speed of sound, to Washington. “I don’t care how many windows you break!” Nasypany yelled at 9:36 a.m.

FROM ABOVE, GOFER 06 pilot Steve O’Brien saw the scene through a haze of smoke and the memory of having witnessed a flight school classmate’s fatal crash. He provided the first confirmation to Reagan National Airport controllers about the plane he’d been asked to follow: “Looks like that aircraft crashed into the Pentagon, sir.”

AT 9:42 A.M., five minutes after Flight 77 hit the Pentagon, FAA national operations manager Ben Sliney had seen enough. Determined to prevent any potential hijacking plots not yet hatched, he issued a second unprecedented, nationwide edict. “That’s it!” he cried. “I’m landing everyone!” Sliney ordered all FAA facilities nationwide to instruct every aircraft flying over the United States to land as quickly as possible at the nearest airport. He marched through the FAA command center and fielded questions from the forty-plus people on his staff, some of whom wondered if their building might be a target and whether the country was at war. Sliney had a direct answer: we’re safe, so let’s get to work. “Regardless of destination!” Sliney shouted. “Let’s get them on the ground!” Sliney’s emergency order to empty the skies would require compliance from 4,546 planes. It would take hours of effort and precise coordination on the ground and in the air. Ultimately, Sliney’s demand would be met by 4,545 of those planes. All but one.

Barely five minutes had passed since United dispatcher Ed Ballinger had warned the pilots of Flight 93 to beware of a cockpit intrusion, followed by Jason Dahl’s unanswered ACARS response that asked Ballinger to “cofirm latest mssg plz.” The narrow window of opportunity to guard the cockpit against a hijacking had closed.

Soon after, Jarrah revealed with certainty that the fourth hijacked plane’s target was in the U.S. capital, although he didn’t specify the exact location. Instead, he dialed a navigational code into the flight computer for Reagan National Airport, located within five miles of landmarks including the U.S. Capitol Building and the White House. Both buildings were targeted by al-Qaeda leaders and operatives at different times during the lead-up to the Planes Operation. Bin Laden reportedly preferred the White House, but Atta thought the home of the U.S. president would be too difficult to reach. He focused instead on the hilltop Capitol, its dome crowned by the bronze Statue of Freedom.

Strangers on a plane minutes earlier, the men and women aboard United Flight 93 called upon their survival instincts and discovered a warrior spirit that some might not have known they possessed. They boarded the flight as airline employees and everyday travelers, bound for home or business meetings or vacations or memorial services, but they emerged from a chrysalis of terror as a fighting band of brothers and sisters. They were at a distinct disadvantage, but they had numbers, they had one another, they had people on the ground who loved them, and they had a collective will that their captors had foolishly underestimated. If they went down, it would be on their terms. Their flight wouldn’t follow the catastrophic model they’d heard about in New York and outside Washington, D.C. Whatever the cost, the hijackers wouldn’t decide their destination. Several minutes before ten, Todd Beamer pulled away from the phone. Lisa Jefferson heard him ask, “Are you guys ready?” Lisa didn’t hear the reply. But next she heard three words, a command that set in motion men and women who’d become their own cavalry: “Okay. Let’s roll.”

AFTER AMERICAN FLIGHT 77 crashed into the Pentagon, Gofer 06 pilot Steve O’Brien asked his crew if they were too rattled to continue flying. They assured him they were fine, so O’Brien pointed the C-130 toward their home base in Minnesota, on a northwesterly route that took them over Pennsylvania. Several minutes after ten, a crew member looking out a window in the back of the plane spotted black smoke rising in the distance. He told O’Brien, who reported to Cleveland Center, that the plume, some twenty miles away, reached some five thousand feet into the air. “You say black smoke in sight?” asked a surprised air traffic controller. “That’s affirmative, black smoke,” O’Brien said. “That’s not a cloud, it’s black smoke, sir.” The crew of the unarmed military cargo plane Gofer 06 had witnessed history for a second time on 9/11; they had seen the aftermath of the crash of Flight 93.

An aide conveyed Cheney’s reaction to a multiagency conference call about airborne threats: “The vice president’s guidance was we need to take them out.” That lethal authorization order reached NEADS at 10:32 a.m., delivered in the form of a message from General Larry Arnold, commander of the Continental Region for NORAD. It read: “Vice president has cleared us to intercept tracks of interest and shoot them down if they don’t respond.” (By “tracks of interest” he meant hijacked passenger jets that refused to heed commands.) Nasypany finally had clear authority. Nevertheless, no one at NEADS shared that order with the fighter pilots circling high over Washington, D.C., New York City, and elsewhere across the country. In fact, the lead fighter pilot from Langley still hadn’t heard anything about hijackings. He still thought he was protecting the capital from Russian cruise missiles. As he flew over the damaged Pentagon, the pilot said to himself, “The bastards snuck one by us.”

AS FIGHTERS PATROLLED the skies over the United States, it remained unknown whether the ground stop ordered by the FAA’s Ben Sliney had interrupted plans for more attacks. One plane that raised questions was United Flight 23, seventh in line for takeoff from John F. Kennedy International Airport, bound for Los Angeles, when flights were halted. Aviation and law enforcement officials told reporters that when the captain announced over the intercom that they were returning to the gate, four young men sitting in first class who appeared to be Middle Eastern became agitated, stood, and consulted one another. They reportedly refused flight attendants’ orders to return to their seats. When the plane reached the gate, the men apparently bolted before they could be questioned.

The most notice given to Major Kevin Nasypany and his team at NEADS was eight minutes before American Flight 11 hit the North Tower. They had less than four minutes’ notice about American Flight 77, and they were told that it was missing, not hijacked. NEADS was notified about United Flight 175 only eleven seconds before it hit the South Tower. The U.S. military’s guardians of the sky received no advance warning and had no knowledge of United Flight 93 before it crashed. In the aftermath, some high-ranking military and political leaders made bold claims, in testimony to Congress and statements to the media, in which they suggested that fighter jets were close to shooting down hijacked jets. Those statements were mistaken.

If they had retaken the cockpit, licensed pilot Donald Greene could have been relied upon to grab the controls, presumably helped by former air traffic controller Sonny Garcia. Flight attendant Sandy Bradshaw could have called her pilot husband, Phil, to guide them to the ground.

The forty heroes of Flight 93 couldn’t save themselves. They couldn’t return home to their loved ones. But they were all that stood between the hijackers and the destruction of the U.S. Capitol or the White House. All deserved to be honored and remembered as civilians turned combatants, the saviors of countless lives during the first battle of a new war.

The toll from inside the four hijacked planes stood at 246 men, women, and children, killed by nineteen suicide terrorists.

Elaine’s office migrated skyward to the 88th floor of the North Tower. She liked that floor even less, especially on windy days when the elevators creaked and moaned as the building swayed a foot or so in either direction.

the towers’ engineers designed each one essentially like a box within a box. The external walls, the outer boxes, were made entirely from thin bands of structural steel. Like the exoskeleton of a crab, those outer walls minimized the need for heavy, bulky internal steel support columns. The external columns gave the towers a look reminiscent of pinstripe power suits, but it was more than a stylistic choice. Fewer interior steel columns meant more rentable space on each acre-sized office floor. Some internal columns were still necessary, so the engineers clustered them in the inner boxes, known as the central core, among the elevators, stairwells, and utility shafts. The result was an extraordinary thirty thousand square feet of rentable, customizable space on nearly every office floor, uninterrupted by columns or walls, with incredible views to boot. Also, the narrow windows between the closely spaced exterior columns tended to reduce dizzying vertigo among people afraid of heights, which oddly enough included the architect, Minoru Yamasaki.

Yet those and other advances came with an unwanted, largely overlooked price: they collectively made the Twin Towers of the World Trade Center more susceptible to fire, especially when compared with older buildings whose exteriors were clad in fire-resistant masonry, whose floors were divided into compartments like the hull of a ship, and whose skeletons contained thicker and more abundant steel.

the old construction code required tall buildings to have a “fire tower,” one stairwell encased in masonry, with an entranceway that trapped and vented smoke away from the stairs. The new rules didn’t require fire towers, so the World Trade Center didn’t have them. Instead, each tower’s three central stairwells were encased in lightweight gypsum wallboard, making them far more susceptible to damage.