Aachen, Germany

Aachen sits at Germany's western edge on the Belgian and Dutch borders with around 250,000 residents. Charlemagne established his main residence here around 794, and 30 German kings were later crowned in the Aachen Cathedral, consecrated in 805 and named UNESCO's first German World Heritage Site in 1978. The city is the birthplace of the 14th-century Aachener Printen gingerbread and home to RWTH Aachen, founded in 1916 and now the largest technical university in Germany. Hot sulphur springs at 46 to 76 degrees Celsius still flow beneath the 1827 Elisenbrunnen pavilion today.