Nemours lionizes its founder, Alfred I. du Pont, in its presentations (the facelift includes a new 5,000-square-foot visitors center) and emphasizes both his solidarity with the gunpowder workers at du Pont's powder mill on the Brandywine River and his enduring philanthropy. He left most of his fortune to establish hospitals and clinics for children, institutions that continue today.

But you cannot grasp how Nemours came to be without exploring the messier aspects of his life. Other du Ponts called him "The Count," but probably not to his face.

In 1902, he moved to keep the DuPont company in family hands by persuading two cousins, Pierre and T. Coleman, to go into partnership to buy it. This corporate triumph would prove highly lucrative, but at the same time his marriage to Bessie Gardner was failing, as was his hearing. After divorcing his first wife and then marrying Alicia, a divorcee, he found himself increasingly ostracized by his relatives. Prickly and high-minded, he also began to fall out with his business partners. In 1911 he was removed as manager of the powder mill and five years later was voted out of the company by a board assembled by Pierre, who had become his nemesis.

Nemours became an enclave du Pont created for himself and his wife against the assault of his clan. He arranged for a nine-foot-high wall to be built around the property, its top studded with broken glass. He is reputed to have said that the wall was "to keep out intruders, mainly those of the name of du Pont."