Chan Chan Archaeological Zone

Chan Chan Archaeological Zone is the world's largest adobe city and the largest pre-Columbian city in South America, covering 20 square kilometers with nine royal compounds that once housed 60,000 people. Erosion from El Niño flooding has damaged the site so severely that UNESCO inscribed it as a World Heritage Site in 1986 and immediately placed it on the Endangered list, with preservation efforts costing an estimated $3 million annually to protect against further degradation.