The first of the du Pont mansions is accessible in Bellevue State Park, 800 Carr Rd (daily 8am–dusk; free). William du Pont Jr converted a Gothic Revival mansion into his own version of James Madison’s Neoclassical home and called it Bellevue Hall. You can’t get inside, but can visit the grounds and see the charming ponds, woodlands, gardens and tennis courts.
Twenty minutes northwest of Wilmington, members of the du Pont family built opulent homes in the rural Brandywine Valley. The Hagley Museum, off Hwy-141 just north of Wilmington (mid-March to Dec daily 9.30am–4.30pm; $11; w http://www.hagley.org), showcases their 1802 founding of a small water-powered gunpowder mill, which grew over the next century to include larger steam- and electricity-powered factories – most of which are still in working order. Be sure to tour the luxurious du Pont mansion, Eleutherian Mills, the centrepiece of the 235-acre estate.
The enormous, dusty-pink Nemours Mansion, just a mile away at 1600 Rockland Rd (tours Tues–Sat 9am, noon & 3pm, Sun noon & 3pm; $15; t 1-800/651-6912, w http://www.nemoursmansion.org), was built by Alfred du Pont in 1910 and named for the family’s ancestral home in France, and is surrounded by a three-hundred-acre, French-style garden. Inside the mansion, you’ll find plenty of lavish rooms including those devoted to fitness, bowling and ice-making, and a collection of early-twentieth-century automobiles. Two miles northwest, off Hwy-52, the one-time du Pont family estate of Winterthur (March–Nov Tues–Sun 10am–5pm; tours $18–40; w http://www.winterthur.org) now displays American decorative arts from 1640 to 1860, each of its 175 rooms showcasing styles ranging from a simple Shaker cottage to a beautiful three-storey elliptical staircase taken from a North Carolina plantation. Separately, the estate galleries present a selection of furniture, textiles, ceramics, paintings and glass in a museum setting.