the mouth of the deceased. The oldest surviving building in the citadel is the Peterskirche (St. Peters Church), which was part of the Benedictine Monastery of St Peter and Paul, after which the hill, and subsequently the citadel, was named. The first recorded evidence of the monastery is from 1060, but it may have existed a considerable time before that. The original building burned down in 1080, but was rebuilt from 1103 to 1147 and St Peter's Church is from this second period. In 1184, the Erfurt latrine disaster occurred in this building, where a meeting of nobles from around the Holy Roman Empire fell through the floor into the latrine, with at least 60 drowning. The city gradually grew more independent during the 12th century, and in 1217 it became fully independent with the founding of its own city council. From 1066 until 1873 the old town of Erfurt was encircled by a fortified wall. About 1168 this was extended to run around the western side of Petersberg hill, enclosing it within the city boundaries. About 1625 the city council had the city wall at the Petersberg strengthened by building a large hornwork and two bastions. These are the bastions named Gabriel and Michael. During the Thirty Years' War (1618–1648), Erfurt was occupied by Swedish forces from 1631. The Swedish king, Gustav II Adolf, hoped to build a fortress on Petersberg hill, but he died in 1632 and the plans never came to fruition. However, the Swedes did strengthen the existing Bastion Gabriel in 1643. In 1664 the city and the surrounding area were conquered by the Electorate of Mainz. On 1 June 1665 the foundation stone of Petersberg Citadel was laid. Building of the citadel The formal first construction phase lasted from 1665 to 1707, following an order from Johann Philipp von Schönborn (1605–1673), Archbishop-Elector of Mainz and Bishop of Würzburg and Worms, to build the citadel. Von Schönborn had recently conquered Erfurt and wanted to build the fortress to demonstrate his power to the local population, in order to suppress any ideas of rebellion. A plan that the Erfurt architect :de:Caspar Vogel (c.1660–1663) had created for the Swedish king Gustav II Adolf served as a basic model for the citadel, and the work was substantially influenced by :de:Antonio Petrini (c.1620–1701) the architect to the imperial court of Mainz. This included the building of the walls, bastions, the