Arequipa

Arequipa demonstrates niche-construction on a volcanic scale—transforming the geological instability that threatens it into the very material of its survival. The "White City" earns its name from sillar, a porous white volcanic stone quarried from the Misti and Chachani volcanoes that loom over the city at 5,822 and 6,075 meters respectively. Sillar is lightweight, earthquake-resistant, and thermally efficient—an architectural adaptation that emerged through repeated destruction and reconstruction since the city's 1540 founding. The UNESCO World Heritage historic center, with its robust walls, archways, and Baroque facades, embodies centuries of seismic stress response encoded in building practice.

This same volcanic geology that demanded architectural adaptation now fuels the regional economy. Cerro Verde, operated by Freeport-McMoRan at a milling rate of 415,500 metric tons of ore per day, produces 19% of Peru's copper and 34% of its molybdenum. The mine contributes 46% of Arequipa region's GDP and nearly 2% of Peru's national GDP—making this Peru's second city economically as well as demographically, with a population approaching one million. The $600 million expansion planned through 2044 will extend operations until reserves are projected to be exhausted in 2052.

Arequipa thus operates through metabolic scaling rarely seen in cities: the largest copper concentrating facility in the world processes volcanic deposits while colonial architecture built from volcanic stone hosts nearly a million residents. Santa Catalina Monastery's 20,000 square meters of cloistered space, the Cathedral's sillar facades, and the 500 colonial mansions all represent the same fundamental transaction—extracting value from what the volcanoes provide while adapting to what they threaten.