Owens-Thomas House.

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Completed in 1819 by British architect William Jay, this gorgeous villa exemplifies English Regency–style architecture, known for its symmetry. The guided tour is a little obsessed with details on aristocratic life, but it delivers interesting trivia about the spooky 'haint blue' ceiling paint in the slave quarters (made from crushed indigo, buttermilk and crushed oyster shells) and the number of years by which this mansion preceded the White House in getting running water (nearly 20).