The “Great Bath” at the site of Mohenjo-Daro in modern-day Pakistan was most likely the first swimming pool, dug during the 3rd millennium BC – about 5,000 years ago. It measures 11.88 meters x 7.01 meters, and has a maximum depth of 2.43 meters.
Two wide staircases, one from the north and one from the south, served as the entry to the structure. A 1 meter wide and 40 centimeters mound is present at the ends of these stairs. A hole was also found at one end of the Bath which might have been used to drain the water into it.
Brick colonnades were discovered on the eastern, northern and southern edges. The preserved columns had stepped edges that may have held wooden screens or window frames. Two large doors lead into the complex from the south and other access was from the north and east. A series of rooms were located along the eastern edge of the building and in one room was a well that may have supplied some of the water needed to fill the tank. Rainwater also may have been collected for this purpose, but no inlet drains have been found.It had a long bathing pool built with waterproof bricks.
“Most scholars agree that this tank would have been used for special religious functions where water was used to purify and renew the well being of the bathers.”