Romans first set up a military camp at the base of what is now Mount St-Jean in AD 275. The site was later a stop during the First Crusade, and by the 12th century, the location of a monastery built for the Order of St. Jean of Jerusalem. The current castle ruins—which include the foundation, a small chapel, and a tower—date from the 1550s, and are cared for by the local historical society. Atop Mt. St-Jean, the commanding view goes deep into Luxembourg to the north
and France to the south.