While the fountain you see today was completed in 1762, the water itself has been flowing to this very spot since 19 BC. It is carried here by the Aqua Virgo, an ancient Roman aqueduct built by Marcus Agrippa, the son-in-law of Emperor Augustus. Legend tells us that Roman soldiers were exhausted and thirsty when a young girl, a 'virgo,' led them to a source of pure water 22 kilometers away. If you look at the top tier of the fountain, above the statues, you can actually see a stone carving of this scene, immortalizing that young girl forever. Scientifically, this aqueduct is a marvel because it is the only one from ancient Rome that has never stopped working. It runs almost entirely underground to protect it from enemies and the elements. Every single second, 120 liters of water gush through this fountain, all powered primarily by gravity. For a practical tip, if you want a quieter moment away from the main crowd, look to the left side of the large basin for the 'Fountain of Lovers,' two small spouts where couples traditionally drink to ensure eternal fidelity.