Perhaps the city"s most surprising feature was a sanitation system that was far beyond its contemporaries. While drainage and private toilets were seen in Egypt and Mesopotamia, they were luxuries of the rich. In Mohenjo-daro, concealed toilets and covered drains were everywhere. Since excavations began, more than 700 wells have been recovered, in addition to a system of private baths, including a 12m x 7m "Great Bath" for communal use. Incredibly, toilets were found in many private residences, and waste was covertly disposed of through a sophisticated, city-wide sewage system.