Essen, Germany

Essen sits on the Ruhr River in western Germany with roughly 585,000 residents and served as the centre of the Krupp steel empire from 1811 onward. The 870 Aldof monastery was founded around 845 by Altfrid, while the 1873 Villa Hügel housed the Krupp family for 80 years. Industry dominates the skyline at the 2001 UNESCO site Zeche Zollverein, a coal mine and coking plant that operated from 1932 to 1986 and ranks as the most-visited industrial monument in the Ruhr. Culture anchors include the 1922 Museum Folkwang, which holds the world's largest collection of German Expressionist paintings, and the 1923 Essen Synagogue, now a House of Jewish Culture. What you find inside that old steel dynasty's library still surprises historians.