The Calzada de los Muertos (Avenue of the Dead) is actually made of a series of walled plazas. Discoloration on the lower plaza walls, makes it apparent that the plazas were flooded 3 to 4 feet with water, making the the long expanse of the avenue a huge reflecting pool to enhance the views from the tops of the pyramids.

Looking up the Avenue of the Dead you get a good view of the Pyramid of the Sun (right) and the Pyramid of the Moon (straight ahead).