Lehner is one of the foremost authorities on the pyramids. His book is a comprehensive study of all aspects of the pyramids - he goes over their evolution from mastabas, to Djoser’s Step Pyramid, to Sneferu’s Bent and Red Pyramids, to the Giza complex, and all the others.
He looks at what the pyramids represented in Egyptian culture, and how he thinks there is good evidence for them being used as tombs. He also talks about building practices and the tools they used. There are lots of pictures, hieroglyph samples, maps and diagrams of the internal architecture of every pyramid in Egypt. The book makes it easy to visualize both the insides and outsides of these structures.
I actually had the privilege of hearing the author speak in person and after the lecture he signed my copy of this book :) I will forever remember that moment fondly.
Lehner admits he does not know all the answers, but the book certainly lives up to its title and provides convincing explanations for when, why, and how these monuments were built.