Porvoo Museum is both a historical museum and an art museum. The Historical Museum is in the Old Town Hall building, which was erected in 1762-64. It and the Cathedral are the most important buildings in the Old Town. The museum is one of two 18th-century town halls still standing in Finland.
According to 19th century engineers, the building was undergoing structural failure. Finnish builders in the 18th century had little experience using stone as a structural material. The foundations were inadequate and soon after its completion the building began leaning, which is especially noticeable in its interior. Nevertheless, the building continued to be used by the town authorities until the 1880s. In 1896 the newly-established Porvoo Museum Association saved it from demolition and opened a museum.
Information from: http://www.porvoonmuseo.fi/index.php?lang=ENGLISH
This image was taken in 1996 by John Schooley, FAIA, during an architectural tour of Finland.