Olavinlinna ("St. Olaf's Castle" or "Olofsborg") is one of the greatest medieval castles in Finland. It was built to secure the eastern border of the Kingdom of Sweden-Finland. The construction started in 1475 by Erik Axelsson Tott. Russians disturbed construction work sequently, because the castle was sited in Savonia to the Russian side of the border established by the Treaty of Nöteborg. Olavinlinna was completed probably in 1483 and there were first a main castle and three towers (Church Tower, Bell Tower and St. Erik's Towers).
Olavinlinna withstood several sieges by the Russians during the First and Second Russian-Swedish wars. Gustav Vasa ordered to erect fourth tower (a "Fat Tower") in 16th century and fifth ("Kilj Tower") was built in the 17th century. The castle was conquered first time by the invading Russians in Great Northern War on 28 July 1714. St. Erik's Tower was badly damaged in cannon fire and Russians demolished it. Olavinlinna was returned to Swedish in Treaty of Uusikaupunki, but they lost it constanly only 23 years later in the end of the Russo-Swedish War of 1741-1743.
Russians enhanced Olavinlinna fortifications and it withstood the siege of Swedish in the war of Gustav III in 1788. The Fat Tower was destroyed in an explosion of gunpowder supply in 1791. When Russians occupied Finland in 1809, Olavinlinna lost its defensive status. It was used as garrison, storage and prison and was abandoded in 1850s. Renovation was started in the end of the 19th century.
Currently, the castle hosts several small exhibitions, including the Castle Museum which displays artifacts found in the castle or related to it, and the Orthodox Museum which displays icons and other religious artifacts both from Finland and Russia. The castle forms a spectacular stage for the Savonlinna Opera Festival, held annually in the summer since 1912.
Olavinlinna is the initial model for Kropow Castle in the comic book King Ottokar's Sceptre, an album in the series of Adventures of Tintin created by Hergé.
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.