Hakasalmi Villa was built in 1843 by the procurator and privy counsellor Carl Johan Walleen as a combined city and country residence. The architect was E.B. Lohrmann from Berlin. Two wings were added to the front of the main building in 1847, the north one served as a bakery and the south one as a greenhouse. The villa was surrounded by a large English garden.
The municipality of Helsinki bought Hakasalmi from Aurora Karamzin in 1896. After her death the historical museum of state was moved to the villa. Since 1911 it has been owned by Helsinki city museum. Today there are changing exhibitions. The villa itself is one of the rare empire-style buldingins still existing in Helsinki.
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.