The Pyramid of the Sun rests on a base measuring 222 by 225 metres and stands 63 metres high. A staircase of 242 steps and five landings leads to the top, which was undoubtedly once crowned with a temple and perhaps even a soaring stone statue.

This pyramid, built using the talud-tablero technique, is not a necropolis and so has no tombs inside. At its base, a small iron door ant the foot of the central staircase opens on to a tunnel 100 metre long that leads to a cavity in the form of a four-leaf clover with a gushing spring.

This womblike symbol of creation lies exactly perpendicular to the summit of the pyramid.