Chan Chan is an ancient city in northern Peru dating back to around 850 AD. This was the worlds largest mud city comprising over 20 square kilometres of now partially restored ruins. Air gaps integrated into the buildings walls were designed for cooling.
Extract from Wikipedia below.
The largest Pre-Columbian city in South America, Chan Chan is an archaeological site in the Peruvian region of La Libertad, five km west of Trujillo. Chan Chan covers 20 km² and had a dense urban center of 6 km². Chan Chan was constructed by the Chimor (the kingdom of the Chimú), a late intermediate period civilization which grew out of the remnants of the Moche civilization. The adobe city of Chan Chan, the largest in the world, was built around AD 850 and lasted until its conquest by the Inca Empire in AD 1470. It was the imperial capital where 30,000 people lived. Chan Chan was added as a UNESCO World Heritage Site on November 28 of 1986.
