The oldest church in Luxembourg City, founded around 987 as the chapel of Count Siegfried's castle on the Bock. Successive rebuilds have left it a layered building — Romanesque foundations, Gothic windows, Baroque interior — and a much smaller scale than the nearby cathedral.
The interior is open in daylight hours, dim and quietly devotional. The square in front is one of the few quiet corners of the old town and a good place for a short pause between sights.