At the Aachen Cathedral, in the city of Aachen, western Germany

 At the border triangle in Dreiländereck (border triangle), one can stroll between Germany, Belgium and the Netherlands, all in a matter of seconds.

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(in western Germany) Aachen is a city in the North Rhine–Westphalia Land (state). Its municipal boundaries coincide on the west with the frontiers of Belgium and the Netherlands. It was a royal residence of the emperor Charlemagne, and it served as the principal coronation site of Holy Roman emperors and of German kings from the Middle Ages to the Reformation. The Palatine Chapel, a masterpiece of Carolingian architecture, is incorporated within Aachen Cathedral, which was designated a UNESCO World Heritage site in 1978.

+ Originally a Roman spa called Aquisgranum, Aachen rose to prominence in the late 8th century during the rule of Charlemagne, becoming his favourite residence and a centre of Western culture and learning. From the coronation of Otto I in 936 until the 16th century, more than 30 German emperors and kings were crowned at Aachen. Aachen was fortified in the late 12th century and granted municipal rights in 1166 and 1215, and it became a free imperial city about 1250. Aachen began to decline in the 16th century. (It was too remote from the center of Germany to be convenient as a capital, and in the 1560s the coronation site was changed to Frankfurt am Main.) Aachen was frequently at odds with the emperors during the Protestant Reformation. In 1656 the city was devastated by a great fire.

+ Aachen hosted several peace conferences, including those ending the War of Devolution (1668) and the War of the Austrian Succession (1748). Occupied by Napoleon’s army in 1794 and annexed by France in 1801, it was given to Prussia after the Congress of Vienna (1814–15). The city was briefly occupied by the Belgians after World War I. It was severely damaged in World War II, and it became the first large German city to fall to the Allies (October 20, 1944).

+The noteworthy medieval churches of St. Foillan, St. Paul, and St. Nicholas were destroyed or heavily damaged during World War II, but reconstruction began soon afterward. The Rathaus (Town Hall), built about 1530 on the ruins of Charlemagne’s palace and containing the magnificent Hall of the Emperors, was also damaged and restored.

+ Depicted here is Aachen Cathedral, which suffered relatively little damage in the war. It incorporates the distinctive Carolingian and Gothic styles. The Palatine Chapel (built 790–805) of Charlemagne, modeled on San Vitale (in Ravenna, Italy), is Carolingian in style, and the choir (ca. 1355) and subsidiary chapels are Gothic. In the gallery of the chapel is the marble throne thought to have been Charlemagne’s; it was long used for coronations. Charlemagne’s tomb is marked by a stone slab over which hangs a bronze chandelier presented by Frederick I Barbarossa in 1168. There are many educational institutions, including the Rhenish-Westphalian Technical University, founded in 1870, the earliest in Prussia,