The Alqueva Dam, with a reservoir covering 250 km² and over 1,100 km of shoreline, is the largest artificial lake in Europe. It covers five municipalities in the Alentejo region: Portel, Moura, Reguengos de Monsaraz, Mourão, and Alandroal, as well as the border municipalities of Olivença, Cheles, Alconchel, and Villanueva del Fresno.

The long period between the initial studies and the construction of the dam, around 50 years, made Alqueva almost a myth among the population. The initial project aimed to irrigate the Alentejo and develop agriculture, which would combat desertification and underdevelopment in the region.

After several years of advances and setbacks, construction began in 1998 and was completed in January 2002. On February 8 of the same year, the floodgates were closed and the filling of the Alqueva reservoir began.

With the construction of the dam, the old village of Luz would be submerged. Thus, after several studies and public consultation, it was decided to build a new village where the inhabitants of the old village were relocated. The Luz museum was also built with a view to preserving the heritage of the old Luz and the region.

The Alqueva Dam is now the largest water reserve in the country. Its electricity production capacity started at 260 MW, enough to supply the district of Beja, and was doubled in 2012 to 520 MW.

The Alqueva reservoir has also created new opportunities for tourism development, adding the Great Lake to a region that already has a long history, evident in its rich architectural, archaeological, and cultural heritage.