Saarlouis (German pronunciation: [ˌzaːɐ̯luˈiː]; French: Sarrelouis, French pronunciation: [saʁlwi]) is a city in the Saarland, (Germany), capital of the district of Saarlouis. In 2017, the town had a population of 34,758. Saarlouis, as the name implies, is located on the River Saar.It was built as a fortress in 1680 and named after Louis XIV of France.