Schwanau castle ruin, Castle ruin on Schwanau Island in Lake Lauerz, Switzerland

Schwanau castle ruin is a fortified stone structure on an island in Lake Lauerz, positioned approximately 465 meters above sea level. The complex displays typical medieval construction methods with foundations and wall remains that archaeologists continue to study.

The castle belonged to the counts of Lenzburg; when that line died out around 1173, the island passed to the Kyburgs, who built the main wall and the ring walls of the residential area between the late 12th and first half of the 13th century. The castle was abandoned after a fire in the mid-13th century and never rebuilt. In 1684 the hermit Johann Linder built St. Johann's chapel on the island; it was destroyed by the Goldau landslide of 1806 and rebuilt by Schwyz governor Ludwig Auf der Maur and his descendants. The canton of Schwyz bought ruin and island in 1967.

The island's chapel, built in 1684 by the hermit Johann Linder, was destroyed by the Goldau landslide of 1806 and rebuilt by Schwyz governor Ludwig Auf der Maur and his descendants. The castle ruins were preserved alongside it, and since 2009 the island has been developed as an excursion destination with a restaurant.

The island of Schwanau lies in Lake Lauerz and is reached by boat from the shore; the crossing is short and the ruin, chapel and restaurant stand close together on the island. The site can be visited while the boat service runs, and the lake level and weather determine whether landing is possible.

After a devastating landslide in the region, the island became a refuge for hermits who lived there in solitude. This chapter remains part of local memory and shows how natural disasters reshaped human presence.