From AFP, August 01, 2004

LIMA: US and Peruvian archaeologists have discovered two Inca observatories in central Peru, which they said are the most imposing of the stone structures found to date.

The discovery of the observatories, announced Friday, is the result of five years of searching in Huanuco province.
One of the two, known as Ushnu, is larger than the observatory of Cuzco, the largest previously found, archaeologist Juan Luis Pino told the local media. It measured 48m long, 32m wide and 4mhigh.
The observatory's principal function was to help the Incas decide where to build according to the positions of the sun and the moon, he said.
Pino said the site continues to be venerated by the local population, although it is no longer used as an observatory.