St. Michael, church building in Limburg an der Lahn, Germany

St. Michael is a two-storey rubble-stone chapel on the edge of the cathedral rock above the Lahn, its lower floor at the old cemetery level and its upper floor at today's Domplatz. The lower storey has a three-bay round-arched ribless cross vault on octagonal corbels; the upper storey is flat-ceilinged. Paired pointed-arch windows with chamfered stone surrounds sit in blank arches, and a steep slate roof carries two small dormers.

St. Michael was built between 1250 and 1270, shortly after Limburg Cathedral was consecrated in 1235. The main altar was donated in 1280 by canon Rorich, followed by a St John's altar given by knight Johann von Brunsberg around 1325 and a St Thomas altar endowed by his brother Dielmann in 1331 and 1345. In 1617 the chapel received a steeper roof with a grain loft beneath it; after a fire in 1853 it was given a flat gable roof and the collapsed east gable was rebuilt from the old stone.

The chapel was dedicated to the Archangel Michael, guide of the dead in Christian belief, and was first recorded as an ossuary in 1359; in 1366 it appears as the "new chapel above the ossuary". A 1445 mention names it St. Thomas, after the Thomas altar donated by Dielmann von Brunsberg in 1331 and 1345. Since 1857 the upper floor housed the city gravedigger's flat.

St. Michael stands at the edge of the Domfelsen, the rock dropping steeply to the Lahn. Its lower floor sits at the old cemetery level, while the upper floor is roughly level with today's Domplatz; the south side was filled in during the 19th century. The original entrance area was only uncovered and reconstructed in the early 21st century, and the former wooden stair to the main south entrance is now a stone stair.

The chapel was first recorded as an ossuary in 1359 and as the "new chapel above the ossuary" in 1366; its lower floor kept that function until the 19th century. From 1857 the upper floor housed the city gravedigger's flat and the mortuary, and it was still lived in in 1907.