Earnaness, Castle ruin in Forshem parish, Götene Municipality, Sweden

Earnaness is a ruined medieval stronghold on a promontory by Lake Vänern at Årnäs in Forshem parish, Götene Municipality. Excavations in 1916–1923 and 1999–2001 uncovered a rectangular tower about 13 by 19 metres with walls four metres thick at the base, joined to a square curtain wall roughly 35 metres on each side. A low wall of rough grey stone and a mound of earth and rubble remain, with a wooden platform and trough below.

Aranäs Castle was built in the mid-to-late 13th century on a promontory in Lake Vänern. In 1304 marshal Torgils Knutsson hosted a reconciliation meeting there between King Birger and his brothers Erik and Valdemar. The castle burned in 1305 when Torgils was arrested; the land passed to Gudhem convent, and nuns lived there around 1349–1359. Excavations in 1916–1923 and 1999–2001 uncovered a rectangular tower about 13 by 19 metres with walls four metres thick.

The name Aranæs appears in Old English as Earnanæs, and scholars have linked it since the 19th century to the place in Beowulf where the hero fights a dragon and dies. The Swedish site is also recorded as Aranæs in Old Swedish and Årnäs today, and the same name was borne by a medieval town in Halland burned in 1256.

The ruin lies in the garden of the 18th-century Årnäs manor, near Årnäs in Forshem parish, Götene Municipality. The excavated castle core sits at the tip of the former promontory by Lake Vänern. The site is a registered ancient monument; the visible low stone wall and the wooden trough on a platform are the main features to look for.

Following the castle's destruction, its territories were granted to the convent of Gudhem, which received royal permission to relocate to a new location. The religious community ultimately chose to establish itself at Rackeby instead, breaking this connection to the ruins.