Sillustani is a pre-Incan burial ground on the shores of Lake Umayo near Puno. The tombs, which are built above ground in tower-like structures called chullpas, are the vestiges of the Colla people, Aymara who were conquered by the Inca in the 15th century. 

Ancestor worship and kinship were integral parts of Aymara culture, and the huge chullpas or "chupa" at Sillustani were built to house the Aymara elite of the immediate pre-Inca and Inca period. The structures housed the remains of complete family groups, although they were probably limited to nobility. Many of the tombs have been dynamited by grave robbers, while others were left unfinished. Similar chullpas are found throughout the entire south Central Andes  with the above ground burial styles going back at least to mature Tiwanaku (ca AD 500-950). 

The architecture of the site is often considered more complex than typical Incan architecture. In contrast with the Inca, who used stones of varying shapes, the Colla used even rectangular edges. While chullpas are not unique to Sillustani and are found across the Altiplano, this site is considered the best and most preserved example of them. [Wikipedia]