Karlsborg Fortress is one of northern Europe's largest buildings and consists primarily of limestone from Omberg. Construction was begun in 1819 on 100 hectares of land. The fortress was to house a garrison of 6,000 enlisted men and an additional 8000 to 10 000 people. The walls were mostly complete in 1830, and after comprehensive visits to other fortresses in Europe, fortress architect Johan av Klen presented plans similar in style to the Winiary fortress in Posen (present-day Poznan).
Karlsborg Fortress was built to realize the so-called central defense idea adopted by the Swedish military after the Finnish and Napoleonic Wars. The site was chose by Baltzar von Platen in connection with the construction of Göta kanal. The intent of the central defense idea was that the King, the Council, the Riksdag and central command functions would, in the event of an attack against the kingdom, pull back and ensconce themselves in this fortress in the middle of the country. Even the gold reserves of the central bank of Sweden were to be safeguarded in the fortress in times of trouble.
Due to its great expense and reduced funding, the fortress wasn't in operation until 1870, and wasn't fully completed until 1909. To compensate for the rapidly evolving technology of artillery during this time, Vaberget Fortress was built in the early 1900s five kilometers west of Karlsborg to provide additional protection to the main fortress.
The town of Karlsborg has sprung up next to the fortress. It was initially mostly living quarters for personnel employed at the fortress, but grew to a sizable community, in part due to Göta kanal which passes through the town.
Ever since the fortress lost its intended central defensive rôle in 1918 it has been used as a garrison for Göta signalregemente, S 2, and since 1984 Livregementets husarer, K 3, are also based there.
Karlsborg has been a Swedish listed building in Sweden (byggnadsminne) since 1935. The garrison church is especially worth visiting. The church is housed in the central building of the fortress, 'the last stand', on the second floor above the Fortress Museum. The church was once intended as an assembly hall for the Riksdag in times of troubles. A chandelier composed of bayonets instead of crystal prisms hangs from the ceiling.References:
The Erfurt Synagogue was built c. 1094. It is thought to be the oldest synagogue building still standing in Europe. Thanks to the extensive preservation of the original structure, it has a special place in the history of art and architecture and is among the most impressive and highly rated architectural monuments in Erfurt and Thuringia. The synagogue was constructed during the Middle Ages on the via regia, one of the major European trade routes, at the heart of the historical old quarter very close to the Merchants Bridge and the town hall. Many parts of the structure still remain today, including all four thick outer walls, the Romanesque gemel window, the Gothic rose window and the entrance to the synagogue room.
After extensive restoration, the building was reopened in 2009. On display in the exhibition rooms is an collection of medieval treasures discovered during archaeological excavations. This includes 3,140 silver coins, 14 silver ingots, approx. 6,000 works of goldsmithery from the 13th and 14th centuries and an intricately worked wedding ring of the period, of which only two others are known to exist anywhere in the world. A mikveh (Jewish bath) has been excavated close by (13th/14th century). The Old Synagogue, the Small Synagogue and two Jewish cemeteries together form a network of historical buildings and sites which vividly portray the role of Jewish life in the history of Erfurt.