Petershausen Abbey was founded as an exempt abbey named after Saint Peter in 983 by Bishop Gebhard of Constance, located on the northern shore of the Rhine river opposite to the episcopal residence at Constance with its cathedral. Gebhard dedicated the monastery church to Pope Gregory the Great and settled the abbey with monks descending from Einsiedeln.
Under Bishop Gebhard III of Zähringen and Abbot Theodoric (1086–1116), the Hirsau Reforms were introduced. In 1097 a filial monastery was established at Mehrerau near Bregenz. As Petershausen sided with the papacy in the Investiture Controversy, Gebhard III in 1103 was deposed at the instigation of Emperor Henry IV. The abbey was closed until 1106, the monks fled to the newly established Kastl Abbey in Bavaria. In 1159 the monastery burnt down, and was rebuilt and extended between 1162 and 1180. Facing the claims of Swabian nobles like the Counts of Montfort, the abbots became supporters of the Imperial Hohenstaufen dynasty. Under Emperor Frederick II (1220–50), Petershausen became reichsfrei, gaining territorial independence.
During the Council of Constance (1414–18), the German king Sigismund of Luxembourg stayed at the abbey and the Petershausen abbot even gained the pontifical vestments from Antipope John XXIII. Nevertheless the monastery declined during the 14th and 15th centuries, pressed hard by Konstanz claiming the status of an Imperial city, as well as by the diocese. The attempts of Prince-Bishop Hugo von Hohenlandenberg to incorporate Petershausen were blocked by Emperor Maximilian I of Habsburg. The abbey was charged by the Konstanz citizens during the Protestant Reformation and the brothers were expelled. It was again ravaged by Imperial troops during the Schmalkaldic War, after which the City of Konstanz in 1548 was incorporated into the Habsburg possessions of Further Austria. The monks did not return until 1556.
Petershausen was finally secularised to Baden in 1802; the library was bought by the University Library Heidelberg. Margrave Charles Frederick of Baden had parts of the abbey rebuilt as a private residence for his sons. The St Gregory Church was demolished in 1832. The remaining premises were later used as a psychiatric hospital and as barracks. They now accommodate a number of administrative and educational functions and the Archaeological Museum of Baden-Württemberg.References:
The Arch of Constantine is situated between the Colosseum and the Palatine Hill. It was erected by the Roman Senate to commemorate Constantine I's victory over Maxentius at the Battle of Milvian Bridge in 312. Dedicated in 315, it is the largest Roman triumphal arch. The arch spans the Via triumphalis, the way taken by the emperors when they entered the city in triumph.
Though dedicated to Constantine, much of the decorative material incorporated earlier work from the time of the emperors Trajan (98-117), Hadrian (117-138) and Marcus Aurelius (161-180), and is thus a collage. The last of the existing triumphal arches in Rome, it is also the only one to make extensive use of spolia, reusing several major reliefs from 2nd century imperial monuments, which give a striking and famous stylistic contrast to the sculpture newly created for the arch.
The arch is 21 m high, 25.9 m wide and 7.4 m deep. Above the archways is placed the attic, composed of brickwork reveted (faced) with marble. A staircase within the arch is entered from a door at some height from the ground, on the west side, facing the Palatine Hill. The general design with a main part structured by detached columns and an attic with the main inscription above is modelled after the example of the Arch of Septimius Severus on the Roman Forum.