Pachatusan, Mountain summit in Calca Province, Peru

Pachatusan is a mountain northeast of Cusco in the Andes of Peru, reaching about 4,842 metres. It stands on the western bank of the Vilcanota River, beside Huaypun to the south-east, above the sanctuary of Señor de Huanca. Its bare brown and tan upper slopes rise over the city below.

For the Inca, Pachatusan held a place in their understanding of the world as a support for the earth, making it a site of spiritual weight long before modern times. In 2009, Peru formally recognized it as part of the national cultural heritage.

Pachatusan takes its name from Quechua pacha (earth) and tusa, a prop supporting a wall or building, so the name means "prop of the earth." Local people venerate the mountain as an apu, a mountain deity, and it stands above the sanctuary of Señor de Huanca.

Pachatusan lies northeast of Cusco, on the western bank of the Vilcanota River, beside the mountain Huaypun to the south-east. The sanctuary of Señor de Huanca sits below the mountain, in San Salvador, and the peak is reached from the districts of San Jerónimo, Saylla and Oropesa. The summit stands at about 4,842 metres (15,886 ft).

Pachatusan is venerated by local people as an apu, a mountain spirit. On February 16, 2009, the archaeological landscape around the mountain was declared a National Cultural Heritage by Resolución Directoral Nacional No. 231/INC.