Irgenhausen Castrum
Irgenhausen Castrum is a Roman fort at Irgenhausen, situated on Pfäffikersee lake shore in Switzerland. It was a square fort, measuring in square, with four corner towers and three additional towers. The remains of a stone wall in the interior were probably a spa. Geography. 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 high drumlin, from the eastern shore of Lake Pfäffikon, situated between Pfäffikon and Kempten, the site of another Roman settlement nearby. History . In the Roman era, along "Pfäffikersee" there was a Roman road from "Centum Prata" (Kempraten) on Obersee–Lake 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 1865 Jakob Messikommer succeeded the dating of finds at Irgenhausen, because of his experience in the dating of peat and concurrent findings at the Irgenhausen Castrum . 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. Architecture. 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 high foundation wall that has an almost square outline of x , and thus an area of  only 0.366 hectares. The fort had four corner towers ( x ), a gate tower on the southeast side and three low towers on the north, west and south front (), and an approximately 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 up to . 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. Cultural heritage. The building is listed in the Swiss inventory of cultural property of national and regional significance as a "Class B" object of regional importance.