Riddersvik, Manor house in Hässelby Villastad, Stockholm, Sweden

Riddersvik is a manor house in Hässelby Villastad, western Stockholm, on the shore of Lövstafjärden. The two-storey main building was completed in 1762, as the portal dated MDCCLXII records, and was enlarged in 1810 with two single-storey side wings. Two red-painted log wings with hipped roofs stand beside it, originally painted in light oil colour.

The estate began as the crown smallholding Flotwijk, bought in 1723 by the bailiff Isac Salmon. In the 1760s the court cellar master Elias von Langenberg the elder built the manor, whose portal is dated MDCCLXII (1762). His son Elias expanded the estate in 1790–1797 by buying most of Lövsta village's land. Stockholm city acquired Riddersvik in 1885 from Anders Mårten Ångman.

The name Riddersvik derives from the old croft Flotwijk, bought in 1723. Since 1972 a Midsummer celebration has been held at the octagonal garden temple on the point, started by Hässelby Schackklubb, which still runs it. The estate also hosts an annual Christmas market, and Walpurgis Night is celebrated in the area.

The manor is used for conferences with overnight stays, so the buildings are not open as a museum. From the manor a garden slopes down to a steamboat jetty on Lövstafjärden, and the garden itself is let out as allotment plots. The grounds are best reached on foot along the shoreline path toward Lövsta, where the temple stands on a small hill.

The octagonal pleasure pavilion called Riddersviks tempel, from around 1800, has a softly curved sheet-metal roof and plastered facades imitating stone, with painted coffers inside the wooden cupola. Since 1972 the Hässelby Chess Club has held the traditional Midsummer celebration here.