Würzburg, Germany

Würzburg sits on the Main in Lower Franconia, Bavaria, with roughly 127,000 residents on a site first settled by Celts and fortified by the Franks around 650 AD. The 1720 Würzburg Residence, designed by Balthasar Neumann and listed by UNESCO in 1981, carries the world's largest fresco, painted by Giovanni Battista Tiepolo in 1750 above an 18 by 32 metre staircase. Above the city, the 704 Marienberg Fortress occupies a 100-metre hill with a well dating to 1200. The 1402 University of Würzburg counts 14 Nobel laureates, including Wilhelm Röntgen, who discovered X-rays in 1895.