Lisbon was formerly provided with clean drinking water by means of the Aqueduct of Free Waters (1729–48), built by Manuel da Maia and stretching for more than 18 km (11 miles) from the water source on the outskirts of the city. The most imposing section is the 35 arches that stride across the Alcântara river valley beyond the Amoreiras shopping complex: the largest of these is said to be the highest ogival (pointed) arch in the world. You can access this section from the Campolide neighborhood (bus 712 and 758 stop nearby). Nearer the city center, another 14 arches run 200 feet along the Praça das Amoreiras, ending in the Mãe d'Agua, an internal reservoir capable of holding more than a million gallons of water. This extraordinary structure is occasionally used for art exhibitions and other cultural displays, giving you the chance to view the holding tank, lavish internal waterfall, and associated machinery.
Calçada da Quintinha 6, Lisbon, 1070-221, Portugal