The Lacus Curtius ("Lake of Curtius") was a mysterious pit or pool in the ground in the Forum Romanum. The area where the Forum would later be built was originally likely a lake, as the area it was in is known to have been surrounded by brooks and marshes. One part of the area was never drained, but gradually became smaller until only a basin, known as the Lacus Curtius, was left. Its nature and significance in Rome's early history is uncertain, and several conflicting stories exist about its history.