If you want to feel your head swim, consider this awe-inspiring fact. When Christ was born two thousand years ago, the Great Pyramid at Giza was already more than two thousand years old. In fact, the Great Pyramid is about 4500 years old. But reproducing it would challenge — and perhaps defeat — the technology and organization of modern America or Britain. It’s the worthy structure that begins a fascinating and enjoyable book called Great Buildings (2012), whose subtitle promises The World’s Architectural Masterpieces Explored and Explained.