Friesenberg Castle (Ruin)

Friesenberg Castle is a castle ruin in Zurich, Switzerland, probably built in the 11th century. It was first mentioned in 1218 in a property description of St. Peter's Church as a landmark. The ruin stands on a terraced spur, Goldbrunnegg, protected by a neck ditch, at an altitude of 658 m above sea level on the eastern flank of the Uetliberg, not far from Uetliberg Cemetery in Zurich's Wiedikon district.

Although Friesenberg Castle geographically formed the extended endpoint of the advanced fortification line Letzi, it was not structurally integrated directly into the Zurich fortification line. Therefore, and also due to the feudal relations at the time, Friesenburg was probably used as a strategic outwork of Regensberg Castle Uetliburg in its last settlement phase.

The history of Friesenberg Castle vividly reflects the changing power relations and the rise of free cities in competition with the hitherto dominant noble families in the 13th century - specifically the history of the city of Zurich, which de facto received the privilege of imperial immediacy from Frederick II as early as 1219, and the Barons of Regensberg.

A document from the County of Kyburg from 1257 refers to Jakob Mülner, the mayor of the Wiedikon court and imperial bailiff in Zurich, as Knight Jacobus Molendinarius de Vriesenberch. It is possible that Friesenberg Castle, as an outwork of the Imperial Bailiwick of Zurich, was administered by a Zurich knightly family, namely the Mülner family, who also owned Wiedikon Castle and Court around the middle of the 13th century. A list from 1321, however, lists Friesenberg as a fief of the Barons of Regensberg and the Counts of Habsburg.

Similar to some of the other five castles on the Uetliberg, the destruction or abandonment of the actual castle complex can no longer be precisely determined. Friesenburg was probably abandoned or destroyed around 1300, as it is already mentioned as a castle site in a property register in 1317.

The abandonment or destruction of the castle complex can therefore be suspected in connection with the increasing conflicts between the House of Habsburg and the Barons of Regensberg - the Regensberg Feud of 1267/1268 or also the "blood feud of 1309" for the regicide of Albrecht I on May 1, 1308. This would explain why in 1321 the Habsburg family and the Barons of Regensberg together, and from 1344 the Habsburgs alone, are said to have been named as owners of Friesenburg. However, it is also possible that Friesenberg Castle was only destroyed in the summer of 1383 (v. Wattenwyl, Geschichte von Bern).

In 1344, the castle site with its associated properties passed "for services rendered" into the possession of the knightly family of Schultheiss Johannes Mülner, whose last descendant died in the Battle of Sempach in 1386.

In 1387, the later Zurich guild master Johann Aeppli bought the castle estate including the associated properties. In 1436, it was acquired by Oetenbach Monastery, and after further changes of ownership, it passed into the possession of the City of Zurich in 1902.

From 1925 to 1930, the ruin, including the outer wall of the core castle and the well clearly set apart from the core castle, was excavated. Due to the improper procedure according to today's archaeological standards and the archaeologically unfounded conservation, most of the different find layers were destroyed, so that only assumptions can be made about the original complex. The defensive wall could have enclosed an area of up to 30 x 18 meters (including the well), and the square keep had a side length of about six meters.

Even with the rather romanticizing reconstruction of the visible wall sections, little care is said to have been taken. The originally rather square ground plan of the keep became a trapezoid, a new window and an archway (portico) are said to have been incorrectly inserted during the partial reconstruction of the ruin.