Founded around 500 BC, Vienna was originally a Celtic settlement. In 15 BC, Vienna became a Roman  frontier city  guarding the Empire against Germanic tribes to the north.

 

 

 

 

 

 

 

 
St. Stephen's Cathedral stands on the ruins of two earlier churches. The south tower, at 450 feet  is roughly the height of a 45-story office building--yet it was built more than 600 years ago, half a millennium before the invention of the modern skyscraper.