Built: The Hidden Stories Behind Our Structures

by Roma Agrawal

After the collapse of the Roman Empire in the fifth century, the Dark Ages –​ or as I like to call them, the Crumbly Ages –​ began, as the Roman recipe for concrete was lost for almost 1,000 years.

Inside is a type of bacteria (normally found in highly alkaline lakes near volcanoes) that can survive without oxygen or food for 50 years. The concrete, mixed with these bacteria-​filled capsules, hardens.

The equivalent of the entire world’s population is moved in an elevator every 72 hours.