The queen for whom Inigo Jones began designing the house in 1616 was James I's Anne of Denmark, but she died three years later, and it was Charles I's French wife, Henrietta Maria, who inherited the building when it was completed in 1635. It's no less than Britain's first classical building -- the first, that is, to use the lessons of Italian Renaissance architecture -- and is therefore of enormous importance in the history of English architecture. Inside, the Tulip Stair, named for the fleur-de-lis-style pattern on the balustrade, is especially fine, spiraling up without a central support to the Great Hall. The Great Hall itself is a perfect cube, exactly 40 feet in all three directions, decorated with paintings of the Muses, the Virtues, and the Liberal Arts. COST: Free. Tube: DLR: Greenwich.