Louhisaari Manor Castle was completed in 1655, and is one of the two palatial manor castles in the Late Renaissance in Finland. However, the basement of one outbuilding dates back to the 16th century. The manor is known as the birth place of Marshal of Finland Carl G.E. Mannerheim. The castle is surrounded by English-style park, and it has a summerhouse built in 1825. Nowadays, the castle is a museum owned by the National Board of Antiquities.