#10
Vienna’s Stephansdom (also known as St. Stephen's Cathedral) is kind of a big deal. As the national emblem of Austria, it attracts over 1 million visitors every year. And rightfully so – at over 800 years old, it’s home to some of the country’s most interesting historical and architectural sights.
The High Altar, which took seven years to build in the 17th century, is just one of 18 altars inside the impressive Gothic and Romanesque structure. The red marble tomb of Emperor Frederick III is decorated with more than 240 statues - that's 6.667 statues for every year of his reign as Holy Roman Emperor.
If your tastes extend to the more macabre, visit the catacombs, built during the 1735 Bubonic plague they're, erm, 'home' to over 11,000 skeletons.