WASHINGTON — A 22-acre estate in Wilmington, Delaware, built by Margaretta du Pont, daughter of former DuPont President Irenee du Pont, is on the market for $5.5 million.

“Glamour, exclusivity and pedigree are combined in this extraordinary offering. The history of this estate is intertwined with the story of Delaware’s greatest dynasty,” said Long & Foster listing agent Stephen Mottola.

Margaretta du Pont and her husband, Crawford Greenewalt, who also served as president of DuPont, built the estate, called Stonehouse, in 1936. The 21,000-square-foot mansion includes nine bedrooms, seven full- and five half bathrooms.

The estate is surrounded by 550 acres of land that du Pont and Greenewalt donated to the Delaware Nature Society.

Also on the property is a guesthouse with a six-car garage and a caretaker’s house with a four-car garage.

You can see the full listing for Stonehouse on Long & Foster’s website.