The aqueduct is classified as National Monument. One of the most remarkable hydraulic engineering works with 58 kms (36 miles) built between 1731 and 1799 in order to supply water to Lisbon. It has 109 stone arches, probably the most known ones are the 14 arches at Alcântara Valley and it resisted to the 1755 earthquake.
In 1967 it was removed from the supply system, however it is possible to do a guided tour at the arches at Alcântara Valley. On the top of the arches there are two footpaths of 941 meters. In the past, the aqueduct was also used to serve as a bridge to have access to the city.
Besides the valley, there is a tank under the Príncipe Real garden and a reservoir at Mãe d'Água das Amoreiras; which is the end of a main section of 14 kms. You can visit some exhibitions at the Water Museum. Also, you can have a glass of wine at the Mother-of-Water Fountain, at the enoteca Chafariz do Vinho.