No huacas or sacred places can be seen around downtown Lima anymore. It is said there was one where the cathedral stands up now but the Spanish just tore it down as it might have happened to many more.
Even though there are many small huacas hidden in the city only two are open for sightseeing. Ironically, they are located in the middle of the most modern districts of Lima: San Isidro and Miraflores.
The most important sacred place which was also regarded as an oracle is just 20 miles south of the city center, though. By the way, all these sites have on-site museums.
As it occurred to most sacred places which were occupied by different peoples before the arrival of the Spanish, this huaca was used as a ceremonial center and as a cemetery. The Maranga culture could have built this site between AD 100 and 200. A ramp leads towards a stepped and adobe pyramid which has been restored lately.
The settlement of this site dates back to about 400 AD and it was occupied by the peoples of Lima, Wari and Ichma. When the Spanish arrived, this site was still regarded as a ñaupallaqta or ancient town with sacred relevance.
Like Huallamarca, it was used as a cemetery as well as a ceremonial center (west side). However, archaeologists have also uncovered squares and chambers for local produce on the east side. They have also found ceramics depicting a man carrying a shark on his back. The cántaro del tiburón or shark´s vessel was broken in religious ceremonies as these peoples depended on the sea for survival.
Pucllana website (in spanish).
More than a ceremonial center, this site was a holy place of pilgrimage and an oracle on the central coast. Pachacamac was considered the Lord of the world and it was represented by the two-faced god made of a piece of wood (there is a replica in the on-site museum).
Pachacamac website (in spanish).