Akapana Pyramid

The Akapana is the largest structure at Tiwanaku. Protzen and Nair put it at about 16.5 metres high and 3.2 hectares in area, against roughly 6 metres and 2.25 hectares for Pumapunku, the other stone-faced platform, a kilometre to the southwest. Published figures for the Akapana's base run from about 182 to 257 metres across, its height from 15 to 18 metres, and its terraces are counted as six or seven depending on the source.

Along the lower level, the outer foundations of the mound are wrapped in courses of rectangular blocks laid with flat bedding surfaces and joints cut square to them. Tiwanaku masons carved each block to its final shape before it was set, so stones of the same type were interchangeable and could be produced in quantity away from the wall.

Almost everything known about the age of this mound comes from things people buried in it. Four dated offerings mark stages in the building of the mound, and their modelled medians fall close together at roughly AD 640 to 660, with wide error ranges around each. One was dug into the Akapana's clay foundation, near the start of the work. Another was recovered from between the retaining wall and the facade of the second terrace, a deposit placed in the gap between two structural walls as that tier went up.

The last of the group is a burial on the summit near a stone conduit. It had to be made after the mound reached its final height, by which time the Akapana was already a layered structure with drainage running through its interior. Together the four dates put the building of the platform in the middle decades of the seventh century, though the spread on each individual date is broad enough that the sequence within that phase cannot be pinned down.