The first historical mention of Gavnø is in King Valdemar's census book from 1231 where a 'house on Gavnø' is mentioned. The house was apparently a castle built to defend Denmark's western coasts. In the 15th century, Queen Margaret I opened St Agnes' Priory there, catering for nuns from aristocratic families. The chapel can still be seen in the castle's southern wing although it has since been extended.
In 1737, Count Otto Thott acquired Gavnø. He renovated and substantially extended the castle, creating today's three-winged, yellow-facaded building in the Rococo style where he was able to house his large collections of paintings, manuscripts and books. At his death, his library collection contained over 120,000 volumes, exceeding that of the Danish National Library. The park surrounding the castle is known for its rare trees, rose garden and, above all, its extensive display of bulbs.
References:The first written record of church in Danmark locality date back to the year 1291. Close to the church are several stones with a Christian text and cross inscribed. The oldest parts of the present red-brick church are from the 1300s. In the late 1400s the church was enlarged to the appearance it has today. The church has been modified both internally and externally several times, among other things after the fires in 1699 and 1889. There are lot of well-preserved mural paintings in the walls.