The Hofburg in Wien, Austria was from the 13th century until 1918 the residence of the emporer. Today it is the seat of the president of Austria and contains other institutions like the Albertina. It was also home to Franz Joseph I. and his wife Elisabeth von Österreich-Ungarn.
The vast building also contains the treasury of Austria, the museum for Elisabeth and the Spanische Hofreitschule. I never took a tour – but it most be worth a try if you’re interested in history.