Seller: Louisa Copeland Duemling

Asking price: $19.5 million

Details: Washington has a new most expensive home topping the market. Tucked back in the Northwest neighborhood of Kent, the five-bedroom, 10,000-sq.ft mansion was for 17 years the home of Duemling, a DuPont heir and active philanthropist, and her diplomat husband Robert Duemling, an ambassador to Suriname and later director of the National Building Museum who died last year. Three fire places, a pool, circular driveway, guesthouse. The Washington Fine Properties listing promises “extraodinary gardens and secret paths” on its six-plus acres.

The gardens at the Duemling home, photographed in 2010. (Melissa Clark/The Washington Post)