Notre-Dame Cathedral is a church founded in the 17th century by the Jesuits. The church owes its current size and neo-Gothic style to a 20th century expansion. The crypt of the church contains the tombs of the grand-ducal family.
Saint-Jean-du-Grund is a church from the very beginning of the 18th century, which once belonged to the Benedictine Abbey of Münster. The interior contains a baroque choir, a beautiful 18th century organ and, in one of the chapels, a black Madonna and Child, carved around 1360, which is the object of great veneration.
The Church of the Trinity is located where a chapel was built in 1313. During the siege of the city by the troops of Louis XIV in 1684, the church and the 17th-century monastery surrounding it were destroyed. From 1737 to 1745, a new church was built on exactly the same spot and was the first large Baroque building in the town. Affected by the French Revolution, the church was transformed into a fodder store and as a theatre. Since 1817, it has been used for Protestant services.