A small, partly rock-cut chapel built into the cliff face on the Pétrusse valley floor. It is the oldest place of worship in Luxembourg, with a small chapel attested on the site as early as 712. The current structure dates mostly from a 17th-century rebuild after fortress engineers blasted away the rock for fortifications.
Usually closed except for the annual procession in spring, but the exterior and the niche with its small altar are visible from the path. Combine with a walk through the Pétrusse Park.