Huaca Huallamarca is a stepped adobe pyramid of the Lima culture, built between 200 and 500 AD, that stands in the middle of a residential block of San Isidro. It was used as a ceremonial centre, then as a cemetery by the Ichma culture much later, and was eventually buried under windblown sand and forgotten until partial reconstruction in the 1950s.
Today it is a clean, terraced pyramid about 20 metres high, with a small on-site museum displaying mummies and grave goods recovered during excavations. Less atmospheric than Huaca Pucllana but easier to climb — visitors can walk all the way to the top platform and look out over San Isidro and the Pacific in the distance.