Aachen is a historic city in western Germany, near the borders with Belgium and the Netherlands. Founded as a Roman settlement, Aachen became the principal residence of Charlemagne in the late 8th century and the political and cultural center of his Carolingian Empire. He began the construction of the city's greatest landmark, Aachen Cathedral, around 796. Aachen was the traditional coronation city of the German kings: from 936 to 1531, 31 German kings were crowned there. Today, the city is known for its cathedral, thermal springs, university, and its location at the crossroads of Germany, Belgium, and the Netherlands.