The first time I went looking for it I was confounded by the fact I couldn't see it. Finally I turned a corner and there it was looming in front. It is amazingly well hidden, especially considering its size, in the middle of a residential district of Miraflores.
I grew up on tales of the Inca who built incredible stone structures so well fitted that one couldn't slide a piece of paper between the stones. The Huaca Pucllana turned many of my presuppositions on their heads. First, Lima is an extension of the Atacama desert receiving somewhere, depending on source, between 5 mm and 2 cm of rain a year. So, given the lack of water erosion, adobe is the building material of choice up and down the coast. Second, the Inca were johnny-come-lately who only held sway for 100 or so years before the arrival of Pizarro and the Spaniards. This huaca had essentially been abandoned 500 years before that. Caral, located a 100km north of Lima and also made of adobe brick, is the oldest inhabited area in the western hemisphere and dates from 2600 b.c.e.
Huaca Pucllana was privately owned until 1981 when it was purchased by the government. I talked to a man in his sixties who spent his childhood using the huaca as a bmx track since it was the only "hill" in the neighborhood. 35 years of excavation have uncovered lots of history, pottery, textiles and 64 tombs. Archaeologists are looking forward to the next 30 since they think the remaining area is potentially even richer than what they've uncovered so far.