To the east of the Pfäffikersee, at the locality Irgenhausen, a fortress has been excavated. Investigations and digging are documented already in 1838 and 1856-1857, and Ferdinand Keller could publish a plan in 1860. In 1897 the demolition of the ruins began, to be used as building material in a factory. Fortunately the terrain could be bought by the Antiquarische Gesellschaft in Zürich, led by Jakob Heierli. Between 1898 and 1909 the fortress was then excavated and restored. The results were published by Otto Schulthess in 1911.
The fortress as seen in 1971. Photo: ETH-Bibliothek Zürich, Bildarchiv, Jules Vogt.Below the fortress remains were found of an older building, probably a villa. Below and next to tower 2, rooms with a hypocaust were found. The fortress was built either around 300 AD or during the reign of Valentinianus I (364-375 AD). It was destroyed by a fire (the Roman troops left the area in 401 AD).
Excavation of a room with a hypocaust in 1907. Photo: Wikimedia, Roland zh (from the information panel).The building was almost square, measuring 60.60 x 61.80 m., with walls 1.90 m. thick. On the corners were square towers measuring 8 x 8 m. They may have been 12-15 m. high. In between were smaller square towers measuring 6 x 6 m. The entrance gate was in the south-east wall (10.50 m. wide, 8.50 m. deep, with an entrance 5 m. wide), in the other walls were secondary entrances, 1.50 m. wide. Each wall also had two vertical slits, 0.20 m. wide. Two buildings were found in the interior: a row of three rooms in the western corner (24.50 x 10.00 m.) and next to that a row of three rooms, two apsidal, presumably baths (11 x 8 m.).
Plan of the fortress. After Schmelzbach et al. 2014, fig. 1b.
View towards the lake. Photo: Wikimedia, Nsevindi87.
One of the restored towers. Photo: Wikimedia, Roland zh.Among the finds were some so-called onion knob brooches, used to fasten soldier's coats.
An onion knob brooch. Photo: Archäologie und Denkmalpflege, Kanton Zürich.
Literature
Keller 1860, 311-314; Schulthess 1911; Unverzagt 1916; Drack-Fellmann 1988, 468-470; Drack-Fellmann 1991, 206-207; Horisberger 2007(2); Schmelzbach et al. 2014.
[30-Mar-2024]
