The Aqueduto das Águas Livres, built between 1731 and 1799 on the order of Dom João V, stretches across the hills into Lisbon from Caneças over 109 arches, with the tallest reaching a remarkable 65m in height at Campolide. This magnificent structure provided Lisbon with its first clean drinking water, yet it also bears a darker notoriety as the place where 19th-century murderer Diogo Alves threw his victims over the edge.