On May 12 1731, the construction of the "Aqueduto das Águas Livres" (Free Waters Aqueduct) was authorized by a royal warrant granted by D.João V. The construction work began in August 1732 and in 1748 the Aqueduct starts functioning, supplying water to the city of Lisbon. Its length, comprehending all its ramifications, is 58 135 metres
Between the sources of "Águas Livres" ( in the area of Belas-Carenque and Caneças) and "Mãe de Água" in "Amoreiras" ( Lisbon ), the Aqueduct is 18,5 km long, reaching 48 km if we include all its ramifications. And if we add the 12 km long distributing pipes to the several fountains, we reach a total length of 60 km!
The channels to convey the water run along underground or aerial channels, ventilated by 137 skylights, on a total of 127 arches.
The most spectacular part, for its majesty, is the range of arches in "Alcântara", is 941 meters long, consisting of 35 arches, 14 of them ogival and the remaining complete. The biggest one is 32 meters large, 65 meters high, and it is the biggest arch of stone ever built in the whole world. Today, "Av. Calouste Gulbenkian"can be seen underneath. Removed from the supplying system in 1967, the aqueduct is not only one of the ex-libris of Lisbon but also one of the most remarkable works of hydrological engineering ever built.
Even today the majesty of this work astonishes us, due to its length and also because of the techniques and materials used, considering the time of its construction (the eighteenth century ).
Above the Aqueduct, on both sides, we can find the sidewalk. It allowed the passage of people and animals between the hills of "Amoreiras" (Campolide) and "Monsanto" (Serafina). This passage was locked up to the public in 1852, since it was not safe, especially at night, due to presence of several thieves. Being the most recalled, "Diogo Alves" who stoled and pushed down the aqueduct his victims. He killed many pople, 4 of them from the same family. Identified and hanged up in 1841. The "Diogo Alves" stone is right over the biggest arch.
This texts were taken, with permission, from the great a geocache dedicated to this aqueduct -
The Aqueduct [Lisboa], by MAntunes.