11 bells in the South tower. Full peal can be heard here: https://www.youtube.com/watch?v=c151mIKhXGE To minimize excess vibrations of the supporting structure, since 2003 the bell's electrical swinging mechanism has been carefully controlled by a computer. An elevator takes visitors up the to the bell. References External links . Individual bells 18th century in Vienna 1950s in Vienna St. Stephen's Cathedral, Vienna