In which country would you find Buckingham Palace?

You would find Buckingham Palace in England. It stands in the City of Westminster in London and serves as the London headquarters and official working residence of the United Kingdom's monarch.

The building began as Buckingham House, a townhouse constructed in 1703 for the Duke of Buckingham. King George III bought it in 1761 for Queen Charlotte, and it was enlarged substantially during the early nineteenth century. Buckingham Palace became the monarch's London residence when Queen Victoria came to the throne in 1837.

The palace is closely associated with royal ceremonies, state visits, official receptions, and the Changing of the Guard. Its famous balcony is used for major public appearances, while the State Rooms open to visitors during much of the summer. The palace contains 775 rooms and has one of London's largest private gardens.

A useful distinction is that England is one of the four countries of the United Kingdom. The palace is in England, while the monarch it houses is the sovereign of the United Kingdom. For this question, “England” is the expected geographic answer.