There are pools/baths dating as far back as the Ancient Greeks and Ancient Egypt however I believe there would have been something far more prehistoric than this (albeit far less advanced). The first heated swimming pool was built by Gaius Maecenas of Rome in the first century BC. Gaius Maecenas was a rich Roman lord. The great bath at the site of Mohenjo-Daro was most likely dug during the 3rd millennium BC. This pool is 12 by 7 meters, is lined with bricks and was covered with a tar-based sealant.