Pachacamac developed on Peru's central coast where the Lurín River valley meets the Pacific desert. Human occupation in the region is much older, but the sanctuary's monumental history is usually traced from about 200 CE, when people associated with the Lima culture built the Old Temple and other adobe complexes. The site's power came from an oracle identified with Pacha Kamaq, a creator and earthquake deity. Pilgrims approached across arid landscapes to consult a sacred authority whose influence eventually extended far beyond the valley.

Successive societies transformed the sanctuary without eliminating its earlier holiness. Wari influence after about 600 brought new burial practices, fine textiles and ceramics, and broader interregional connections. Later, the local Ychsma polity built numerous stepped pyramids with ramps, compounds often interpreted as elite or administrative centers. Adobe walls, plazas, roads, storage spaces, cemeteries, and residential areas formed an extensive sacred city. Political control changed, but rulers benefited from associating themselves with an oracle already respected by diverse coastal and highland communities.

The Inca incorporated Pachacamac in the fifteenth century while allowing the oracle to retain prestige. They constructed the Temple of the Sun on a commanding ridge, an acllawasi for chosen women, and facilities for pilgrims and administrators. Imperial roads linked the sanctuary to the wider Tawantinsuyu. Inca architecture and state ritual reframed the site, yet the deity Pacha Kamaq was not simply replaced. This accommodation illustrates an imperial strategy of absorbing regional cults and making their authority serve a larger political order.

Spanish invaders reached Pachacamac in 1533 while seeking the ransom treasure of the captive Inca Atahualpa. Hernando Pizarro's party violated the sanctuary and its idol, seized precious objects, and challenged the oracle's power. Colonial extirpation, looting, new settlement patterns, and religious change led to abandonment of many buildings. Windblown sand protected some remains, but grave robbing caused severe loss. Early European accounts, however biased, combined with archaeology provide rare evidence for the sanctuary at the moment of invasion.

Scientific investigation began unevenly in the nineteenth century and expanded with excavations by Max Uhle in the 1890s, whose stratigraphic work helped establish a chronological framework for Andean archaeology. Peruvian researchers, including Julio C. Tello, continued study and conservation. Arturo Jiménez Borja founded the site museum in 1965, creating a local institution for finds that had often left their contexts. A new museum opened in 2016, displaying the carved wooden Pachacamac idol, textiles, ceramics, offerings, and materials spanning more than a millennium.

The Archaeological Sanctuary and Site Museum now protect a vast complex increasingly surrounded by metropolitan Lima. Research continues to revise interpretations of pilgrimage, gender, production, and political control, while preservation confronts earthquakes, humidity shifts, wind erosion, and urban pressure. Visitors move among largely earthen structures whose subdued surfaces once carried color and controlled ceremonial experience. Pachacamac endures because many societies chose to build beside, over, and in dialogue with earlier sacred places, making the landscape an archive of religious continuity and imperial change. The sanctuary's scale makes clear that pilgrimage required food, lodging, administration, security, and labor as well as ritual belief.