"Tiwanaku monumental architecture is characterized by large stones of exceptional workmanship. In contrast to the masonry style of the later Inca, Tiwanaku stone architecture usually employs rectangular ashlar blocks laid in regular courses. Their monumental structures were frequently fitted with elaborate drainage systems. The drainage systems of the Akapana and Pumapunku structures include conduits composed of red sandstone blocks held together by ternary (copper/arsenic/nickel) bronze architectural cramps. The I-shaped architectural cramps of the Akapana were created by cold hammering of ingots. In contrast, the cramps of the Pumapunku were created by pouring molten metal into I-shaped sockets.[19] The blocks have flat faces that do not need to be fitted upon placement because the grooves make it possible for the blocks to be shifted by ropes into place. The main architectural appeal of the site comes from the carved images and designs on some of these blocks, carved doorways, and giant stone monoliths.[20]"
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