Why did the Inca dig thousands of holes in this mountain?
Monte Sierpe, or the “Band of Holes,” sits in the Pisco Valley of southern Peru’s Andes and dates back to at least the Late Intermediate Period (around AD 1000–1400), continuing into Inca times. This striking site features a winding band stretching exactly 1.5 km along a hillside ridge, divided into roughly 60 blocks that hold about 5,200 neatly arranged circular depressions—each usually 1–2 meters wide and 0.5–1 meter deep, with the deeper ones matching the “one meter” detail. New 2025 research using drone mapping and sediment analysis suggests these weren’t random pits but a pre-Hispanic barter market later adapted by the Inca as a massive “accounting device” similar to a giant khipu for tracking tribute and trade. Pollen traces from items like maize and bulrush point to active exchange, with no signs of burials, farming, or fortifications. The layout—rows of 6–9 holes across, separated by gaps—reveals numerical patterns that back its role in organized trade along Andean routes. Located near Ica, about 35 km inland, it’s hikeable but dry, so pack water.