Teotihuacán’s Pyramid of the Moon rises at the northern end of the Avenue of the Dead in central Mexico. The ruins of the city, which was one of the ancient world’s greatest metropolises, are the most perplexing mystery from the pre-Columbian era. Click the above image to enlarge, click to view my high-resolution photo gallery, or click to read my feature article “Teotihuacán: Down the Avenue of the Dead.”