Domaine du château de Montjean, Public park in Wissous, France.

Domaine du château de Montjean is a 17-hectare public park in the Montjean plain, the largest in Wissous, classified as a sensitive natural area. Its lawn, dotted with small white flowers, is bordered by tall pale-leaved trees and a massive dark evergreen with a thick trunk. The Rungis stream runs buried in an underground pipe beneath several metres of rubble, and the castle itself is partly walled up.

The castle was built in the early 1800s and later served as a military hospital during the first World War. During the second World War, the grounds were occupied by German troops.

The estate hosts annual medieval re-enactment events, held there in years such as 2006, 2007 and 2016. Its restored stables are used by the Wissous horse-and-carriage association (formerly the Montjean carriages), with the commune's agreement, so horses and carriages can often be seen beside them. The name Mont-Jean, on the oldest plans, likely came from the estate's first owner.

The park lies in the Montjean plain between Wissous and Rungis, with the A6 motorway along its western edge and the Paris horticultural centre to the north. The Rungis stream now runs buried in a pipe beneath several metres of rubble, and the Meridienne verte passes just east of the grounds. The château itself is unoccupied and partly walled up, but its restored stables house the Attelages de Wissous, so horses and carriages can often be seen nearby.

On 7 November 1824, aeronaut Jean-François Dupuis-Delcourt, later founder of the Société aérostatique et météorologique de France, launched the first flight of an experimental "aeronautic flotilla" from the estate. It rose to 2,600 metres before landing at Choisy-le-Roi.