Temple of the Moon, Archaeological complex in Cusco, Peru.

The Temple of the Moon is an Inca ceremonial site on the north side of Huayna Picchu, 390 m below the summit. It combines an overhanging cave with cut-stone walls, a tall double-jamb doorway and further structures. Inside are a stepped rock carving, six trapezoidal niches and a rock altar in front of the cavern.

The Temple of the Moon dates back about 1,500 years and was rediscovered in 1936. Its purpose is not exactly known: theories include a royal tomb, a place of worship, a look-out post, a sacrifice site, or a ceremonial bathing complex. The name, like many at Machu Picchu, was given arbitrarily.

The name was given arbitrarily, like many at Machu Picchu; one suggestion links it to moonlight falling into the cave. The stonework is said to show the three Inca planes: the condor for Hanan Pacha, the puma for Kay Pacha and the snake for Ukju Pacha. A similar site near Ollantaytambo, Choquequilla ("Golden Moon"), is also called Temple of the Moon.

The site lies 390 m below the summit on the north side of Huayna Picchu, reached from the main Huayna Picchu trail near the saddle. That lower trail is easier and safer than the exposed summit route, but still hazardous, with a steel handrail cable at a few spots. Allow at least 45 minutes each way, and an hour down plus 45 minutes back up if starting from the summit.

The site was rediscovered in 1936, and its name was assigned arbitrarily, as with many Machu Picchu sites. Some speculate the name comes from moonlight radiating inside the cave at night. The trail from the Huayna Picchu summit is exposed and slippery, with a steel handrail cable at a few spots.