Irgenhausen Castrum

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For other uses, see Irgenhausen.
Kastell Irgenhausen
Irgenhausen - Castrum IMG 8164.JPG
The castrum as seen from the west (April 2010)
Irgenhausen Castrum is located in Switzerland
Irgenhausen Castrum
Location within Switzerland
General information
Classification Historic monument
Town or city Irgenhausen
Country Switzerland
Coordinates 47°21′30″N 8°47′33″E / 47.358333°N 8.7925°E / 47.358333; 8.7925
Construction started ~ late 3rd or 4th century AD
Completed ~ late 3rd or 4th century AD

Irgenhausen Castrum is a Roman fort in Irgenhausen, Switzerland. It was a square fort, measuring 60 metres (197 ft) in square, with four corner towers and three additional towers. The remains of a stone wall in the interior were probably a spa.


as seen from the south
as seen from the northwest
as seen from the southeast

The castrum is situated on the Bürglen hill in Irgenhausen, a village of the municipality of Pfäffikon in the canton of Zürich in Switzerland. Bürglen (Swiss German: "small castle") is a 25 metres (82 ft) high drumlin, 400 metres (1,312 ft) from the eastern shore of Lake Pfäffikon, situated between Pfäffikon and Kempten, the site of another Roman settlement nearby.


In the Roman era, along Pfäffikersee there was a Roman road from Centum Prata (Kempraten) on OberseeLake Zürich via Vitudurum (Oberwinterthur) to Tasgetium (Eschenz) on the Rhine. To secure this important transport route, the castrum was built. The native name of the fort is unknown: Irgenhausen was mentioned in AD 811 as Camputuna sive Irincheshusa, so maybe the castrum's name was Cambodunum, the Roman name of the neighboring village of Kempten.

In 1897 stones of the ruined building (believed at the time to be those of a medieval castle) were used for the construction of a factory nearby; the dilapidation was stopped by the Antiquarische Gesellschaft in Zürich in order to start archaeological investigations, carried out between 1898 and 1908, and to preserve the walls. The castrum was set under federal protection as Kastell Irgenhausen in 1909. Walter Mittelholzer made an aerial exploration of the fort and the surrounding area, whereupon in the closer environment Roman villae rusticae, among them one in Kempten, were localized and excavated. In 1957, the land and the castle were sold to the community of Pfäffikon.


Excavations in 1907 showing the hypocaustum of the villa rustica, with the castle wall to the left

For the dating of the fort there are two theories: the first assumes that the fort was built at the time of the Emperor Diocletian around AD 294/295. The other theory, based on the Roman coins found inside the castrum, dated the construction from 364 to 375, in the era of the Emperor Valentinian II. As early as AD 400 the castrum was evacuated and destroyed by Alamanni invaders.

The excavations restored a 1.4 metres (5 ft) high foundation wall that has an almost square outline of 60 metres (197 ft) x 61 metres (200 ft), and thus an area of only 0.366 hectares. The fort had four corner towers (8 metres (26 ft) x 8 metres (26 ft)), a gate tower on the southeast side and three low towers on the north, west and south front (6 metres (20 ft)), and an approximately 1.9 metres (6 ft) strong enclosing wall. The materials used by the Roman soldiers derived from glacial deposits, furthermore, there is a mixture of sernifite from Glarus, limestone and conglomerate. The walls of the towers measure between 1.2 metres (4 ft) up to 1.4 metres (5 ft). The main access was from the south through the gate in the middle of the eastern front. The other three sides hade small side entrances.

In addition to the remains of the towers and surrounding wall, there were found the remains of stone interior buildings: a three-roomed building was seen as a spa. Another building with three rooms has been interpreted as principia, the headquarters of the fort. At the southern corner tower a hypocaust system of an older villa rustica from the 1st to the 3rd century was excavated. The other buildings were made of wood and therefore cannot be individually identified. However, some military barracks, a horreum and a praetorium was probably built inside the fort. In the middle of the hill there was a sunken room. Most of the relics found inside the fort date from the 2nd and 3rd centuries AD and are thought to be relics of the villa rustica on whose ruins the fort was built. At the present time, a red ribbon in the wall shows where the Roman wall ends and the restored wall begins.



  • Beat Horisberger,Bettina Hedinger, Florian Hoek, Roger Büsser: Römisches Landleben im Zürcher Oberland. Huber + Co. AG, Frauenfeld 2007. ISBN 3-7193-1441-3
  • Antiquarische Gesellschaft Zürich: Zeitreise: Irgenhausen. Archäologische Entdeckungen rund um das römische Kastell Pfäffikon Irgenhausen: von der Jungsteinzeit bis zu den Ausgrabungen vor hundert Jahren. Zürcher Oberland Buchverlag, Wetzikon 1999. ISBN 3-85981-196-7

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