In 1211 Riga's archbishop Albert inaugurated Theodorich as the bishop of Estonia. The centre of the bishopric was to be in Lihula. The Construction of the Bishop's Castle began after the conquest of Estonia, namely in 1238 and it was finished in 1242. The bishop shared the castle with the Order. Their relationship became however quite tense and the bishop soon began to look for a more peaceful location. In 1251 the bishop moved to Old-Pärnu and in 1279 to Haapsalu.
The main castle was located on an oval-shaped hilltop, surrounded by a wall, which was at the same time an outer side of the buildings. The north and west sides of the hill were steep, the south and east sides shelving. For that reason the castle was protected from the south and east with two outworks separated by dry moats and stone walls.
During the Livonian War (1558-83) the castle repeatedly changed hands and it was greatly damaged. It was last besieged in 1581. After the war it was decided that the castle would not be restored and in 1643 the Queen of Sweden gave the permission to demolish it.
In 1990-1996 archaeological excavations were carried out on the east side of the main castle, where the walls of the pre-defence system of the main gate were uncovered. Research has shown that the Bishop's Castle of Lihula is one of the most unique defence buildings from the 13th century in the Baltic.
Reference: Lihula Museum
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.