With a sprawling scale that is appropriate given the vast extent of the Hapsburg empire at its peak, the magnificent Hofburg Palace is a city unto itself, with more wings than you could ever explore. With its classic Viennese Fiaker horse carriages in front, the St. Michael's Wing was built in the late 19th century to baroque designs by Fischer von Erlach the Younger. Passing under its dome leads to sumptuous rooms filled with 18th- and 19th-century furnishings. The former apartments of Archduke Stephan are now a museum devoted to the beloved Empress Sisi, the Princess Di of her day. The Imperial Treasury displays the crown jewels, while the Neue Burg (New Castle) wing holds the armory. The main Hofburg entrance is on the vast Heldenplatz (Hero Square), flanked by the lovely Volksgarten and Burggarten parks, the former famous for its roses.