LISBON – Lisbon, considered among the most attractive European capitals, hides under its streets a labyrinth of tunnels and passages that formed part of a complex system of underground canals that helped end the scarcity of potable water in the city more than two centuries ago.
This underground city was built in the 18th century as part of a project to quench the thirst of Lisbon, which could not use the water of the Tajo river due to its high salinity levels.
The tunnels form a network spread over 32 km that begins at the bottom of the Aguas Livres aqueduct, which has been submitted for selection as a UNESCO World Heritage site.
Just two-kilometers of the extensive network have been opened for the public for guided tours in small groups to conserve the historical site and avoid possible problems due to lack of space.
At a depth of 3.5 meters (11.5 feet), the excursions allow visitors discover a Lisbon very different from the city’s overground landscape displayed on the photos hung along the walls of the tunnels, which illustrate the route and help the visitors find out exactly where they are.
Jose Dias, a tourist guide, told EFE that this network of tunnels helped transform the city and create a “new Lisbon” that once competed with the biggest European capitals of the time, like London and Paris.
“The most striking thing (about the tunnels) is the architecture. The entire project was built by hand because there were no electronic tools at the time,” Dias said before climbing down into the labyrinth.
The network was built during the reign of Joao V.
Historian Barbara Bruno, who accompanies the guided tours, told EFE that due to Tajo’s waters being unusable, the king decided to build an aqueduct to fetch water from the banks of the Caranque river in the Bela region of the Sintra district.
The construction of the Aguas Livres aqueduct began in 1731 and the entire system of tunnels and canals took over a century to complete, a mammoth enterprise which justified itself when each person in Lisbon was able to receive four liters of drinking water per day.
The distribution was based on the social hierarchy, with the Nobility getting the first preference, followed by soldiers, industry and hospitals.
Every year, around 1,600 tourists visit the passages that are just 1.64 meter high in parts and have a width of 1.2 meters.
Of the 58-kilometer length of the aqueduct, currently the most important stretch is the section that goes over the Alcantara Valley on the outskirts of Lisbon.
The 941-meter long stretch is made of 35 arches, including the biggest stone ogival arch in the world, with a height of 65.29 meters and width of 28.86 meters.
The construction of the aqueduct, which has been a national monument since 1910, was made possible through a special tax on essential items such as oil, wine and meat.
A dark chapter associated with the architectural marvel is the story of the “aqueduct murderer,” a Spanish-born serial killer called Diogo Alves, who is believed to have murdered over 70 people between 1836 and 1840 at the site.
Alves, who robbed and killed his victims on the aqueduct before dumping them down from its heights, was one of the last people executed – in 1841 – in Portugal for civilian crimes, while the aqueduct remained close for public for decades afterwards.
Although its importance diminished towards the end of the 19th century once alternative drinking water sources were established, the aqueduct continued to supply water for other uses – mainly agriculture – until 1967, before being made a part of the Water Museum.