Burg Rothenfels, Medieval castle ruin in Immenstadt, Germany

Burg Rothenfels is a ruined spur castle on a wooded hill at 853 m above sea level northwest of Immenstadt, overlooking the Kleinen Alpsee. Its walls are built of local Nagelfluh rock with rubble infill; a four-metre stretch of massive Nagelfluh blocks survives on the west side, and the plateau shows rubble from the early 19th-century demolition. The site is not freely accessible.

The Lords of Schellenberg built the spur castle in the second half of the 13th century; by 1273 it belonged to Rudolf von Habsburg and from 1332 to Count Wilhelm II von Montfort. Lightning destroyed it in 1462 and it was rebuilt. In 1816/18 the largely intact complex was demolished for a stud farm, leaving only remnants; Immenstadt acquired the ruin in 1875.

The name Rothenfels refers to the red rock of the site. The castle formed a double complex with Burg Hugofels, only about 170 metres away, and the area between them, with a shared outer gate, is still inhabited today. The castle quarry lay directly behind the partly preserved residential tower of Hugofels.

The ruins are not freely accessible because the masonry is severely endangered; do not enter the crumbling walls. A modern information panel was installed on the site in 2007 as part of the Burgenregion Allgäu. The castle lies at 853 m above sea level on a spur above the Kleinen Alpsee, northwest of Immenstadt.

The castle was destroyed by lightning in 1462 and rebuilt, then largely quarried away in 1816/18 for a foal farm and stud. The rubble heaps from that demolition are still visible across the plateau, and a lithograph by Xaver Glötzle (around 1850/60) records the site as demolition began.