The north tower was the world's tallest building from 1647 (when the taller spire of St. Mary's Church, Stralsund burnt down) until 1874 (when the tower of St. Nikolai's Church in Hamburg was completed). The planned south tower was never built and as a result, with its characteristic asymmetrical form, the cathedral is now the premier landmark of Alsace. One can see 30 kilometers from the observation level, which provides a view of the Rhine banks from the Vosges all the way to the Black Forest.