There were originally two wooden chapels in Kustavi, one in Vartsala (first record from the year 1554) and another in Kunnarainen (1675). In 1783 Kunnarainen chapel was moved to the current site and reconstructed by J. Höckert. The new parish church was named after the king of Sweden, Gustaf III. The church was enhanced between years 1876-1879 and again in 1928.
The pulpit dates back to the 1640s. There are also couple of beautiful miniature ships (so-called votive ships) made by local islanders. The church environment is a well-preversed sample of wooden architecture in Finland.
Kakesbeck is one of the largest medieval fortifications in Münsterland and the oldest castle in Lüdinghausen. The imposingly grown complex originated in 1120 as a motte, a small hilltop tower castle. After numerous changes of ownership, the castle was extended onto two islands, but it was not until the 14th century that it underwent significant alterations and extensions under the von Oer family. The estate experienced its heyday in the middle of the 18th century, when it covered an area of almost one square kilometre and consisted of five further outer castles in addition to the core castle, which were secured by ramparts and moats.
The well-maintained condition of the castle today is thanks to the late Wilfried Grewing, the former lord of the castle. The foundation named after him has been particularly committed to preserving the property since 2020.