St. Stephen's was built in the 12th century. It was virtually destroyed by fire in 1258, and damaged extensively during the Turkish siege of 1683 and during the Russian bombardment of 1945. It was restored and re-opened in 1948. There are 343 steps in the south tower, from which you can view the Vienna Woods, or you can take the elevator in the north tower where you can view the city and the Danube.
The picture above had to be taken with three different shots, as the building is so huge, which is why the picture looks a little strange. The picture on the right is one taken from a magazine.