Wilmington's strength is the Brandywine Valley — the wooded river valley a few miles north of the city that the du Pont family settled in 1802 and progressively built into an extraordinary cluster of estates, gardens, and museums. The Hagley powder works, Winterthur, Nemours, and Longwood (just over the Pennsylvania border) make up most of a long weekend on their own. Add the Riverfront, the Delaware Art Museum, and a wander around the historic blocks downtown.