Ruine Tegerfelden, castle ruin in Tegerfelden, canton of Aargau, Switzerland

Ruine Tegerfelden is a ruined hilltop castle on a rocky spur of the Ruckfeld above Tegerfelden in the canton of Aargau, Switzerland. The first building phase had only a stone manor house, with other structures in wood, secured by a palisade and two ditches on the mountain side. After a fire at the end of the 12th century, the castle was rebuilt with a stone tower, ring wall and another stone building, plus two half-timbered houses on base walls; in the early 13th century a half-timbered house with a cellar was added. Excavations between 1948 and 1958 conserved the tower remains, part of the ring wall and the base of one house, while the rest was reburied; follow-up repairs took place in 1966, 1971, 1986 and 2008.

The castle was founded in the late 11th century by the noble family of Tegerfelden, who held regional power for several generations. After a major fire around 1250, the castle was not rebuilt and fell into decline, appearing in documents by 1269 already classified as a ruin.

The name Tegerfelden comes from the Freiherren von Tegerfelden, the noble family that built the castle. The line ended with Walter III, last documented in 1254; his daughter Ita and her husband Ulrich von Klingen took over the inheritance in 1236. A Konrad von Tegerfeld was among the conspirators in the murder of King Albrecht I.

The ruins are freely accessible with walking paths around the stone remains that let visitors explore the site's layout at their own pace. Wear sturdy shoes and exercise caution around the exposed stonework and unguarded edges.

Konrad von Tegerfeld, a member of the family that held this castle, was among the conspirators in the murder of King Albrecht I. The killing was carried out near Windisch in 1308 by the king's nephew Johann Parricida and his accomplices. The name is spelled Tegerfeld, not Tagerfeld.