Sulabh International Museum of Toilets Delhi

More than half of India's 1.3 billion people still don't have a toilet in their homes, but since 1970 the Sulabh NGO has worked to address India's sanitation issues, constructing new public toilets. The organisation also educates, and their small, quirky museum traces the history of the water closet from 2500 BC to modern times. It's 650m south of Dashrathpuri metro station, straight along the main road.