Built in the 18th century, the Águas Livres aqueduct runs across and through Lisbon and offers some of the best views of the city. It is a well-preserved series of 109 stone arches and was built in 1744 to bring clean drinking water to the city's residents. The historic structure still stands tall and survived the massive 1755 earthquake without damage. The main arches extend for 18 kilometers, with the entire aqueduct being almost around 60 kilometers long. At its highest point the arches rise 65 meters high. It was the largest arch in the world at the time of its construction.

A walk along the top grants viewpoints on both sides of the city's river. Although high up, the passageways are wide and the Museu da Água (Water Museum) at its base explains the history of the complex water systems and structures here.

There is a sign outside the ticket office with an overview drawing of the entire canal and a few explanations,nothing more.I came by bus and got off at Campolide station, which is almost directly under the Aqueduct. You could take some good photos from there, but then you have to go up the steep path to get to the Museu do Agua, where I entered the area. Outside the ticket office there is a sign with an overview of the entire canal and a few explanations. I was the only visitor, but there shortly before 5 p.m. (5 p.m. was the last entrance, the gates closed at 5:30 p.m.); The employee there was visibly not happy that a visitor actually arrived shortly before 5 p.m.

30 minutes is actually more than enough for the visit. I enjoyed the views with the evening sun over the Lisbon skyline. Absolutely worth a visit if in the area! OUV? No, not at all IMO.