Kasteel Van Oostkerke is a medieval castle located in the village of Oostkerke, part of the municipality of Damme in West Flanders, Belgium. The castle's history begins around 1300 when a fortified brick tower was first constructed, and by the end of the 14th century it had developed into a complete fortress featuring both an "Opperhof" (upper court) and "Nederhof" (lower court), both surrounded by protective moats.

After centuries of decay and damage from occupations, pillages, and flooding during World War II, the castle was purchased by Baron van der Elst, a Belgian diplomat, who undertook a comprehensive restoration in 1938.

During this restoration, the ramparts were deepened, the stone entrance bridge was repaired, and the west wing was replaced with an elegant Renaissance-style building. The medieval foundations of the ring walls and towers were raised to serve as ornamental features and garden pathways.

Baron van der Elst commissioned the renowned Dutch landscape architect Mien Ruys (1904-1999) to redesign the grounds. Ruys, one of the most celebrated garden architects of the 20th century, created a garden design inspired by Flemish Primitive art that flourished between the 14th and 17th centuries. The resulting garden features several distinct areas including an enclosed inner courtyard garden, a Maria garden, and a rose garden, all seamlessly integrated with the surrounding meadows and connected by footpaths that follow the ancient medieval foundations. 

The castle today combines medieval fortification elements with Renaissance refinement and is surrounded by meticulously maintained gardens that showcase Ruys's innovative approach to landscape design. The estate remains privately owned by the van der Elst family and is not open to the public, though it continues to be recognized as one of the most beautiful gardens in West Flanders.