About 8km (5 miles) south of Trujillo in the desert Valle de Moche, this complex of Moche ruins is enigmatic from a distance. Two imposing rounded-off and weathered adobe pyramids, partially eroded, sit in a dusty open field at the foot of Cerro Blanco. Built by the Moche people around A.D. 500, they are about 7 centuries older than the ruined city of Chan Chan. The two masses constituted a religious center and an urban settlement.

The first pyramid, the Huaca del Sol (Temple of the Sun), is nearly 20m (66 ft.) high, although it was once bigger by perhaps two-thirds, and it was very likely the largest man-made structure in the Americas in its day. Heavy rains of the El Niño phenomenon, and the Spaniards' diversion of the nearby Moche River, precipitated the erosion. It is said to have been built by 250,000 men and 140 million adobe bricks. The pyramid once surely was composed of multiple staircases and platforms. The huaca remains unexcavated, and it looks very fragile, as though a major rainstorm could easily take it out. Signs warn visitors against climbing on the ruins (NO ESCALAR), but plenty do climb up to the top along steep trails. Additional foot traffic only furthers the erosion, though, and the views are equally good from the Huaca de la Luna across the way. Some visitors inevitably find this lumped mass a bit of a disappointment, just a massive mound of muddy earth; if you find yourself in that camp, hurry over to the neighboring huaca.

Across the open field, where burial sites have been found and living quarters were once erected, is the smaller but more interesting Huaca de la Luna (Temple of the Moon). It is better preserved than the Temple of the Sun and has been excavated; many of the most important finds took place in the 1990s, and excavations are ongoing. The structure consists of five independent levels, with no communication among them -- perhaps a result of the fact that the huaca (pyramid) was constructed in major phases over 600 years. Inside the adobe walls (at the top of an entrance ramp) are polychromatic friezes of large rhomboids, featuring a repeated motif of the fearsome anthropomorphic figure Ai-Apaek, known as El Degollador (the decapitator), and several secondary figures. The yellow, red, white, and black designs are quite remarkable; the god is said to have the hair of the sea and eyes of an owl. From the top of the Huaca de la Luna, there are excellent views of Huaca del Sol and the surrounding countryside. Near the ticket booth, where you can arrange for a guide, is a small refreshment stand and souvenir shop.