The imperial city of Aachen, charmingly located on the border of Germany, Belgium and the Netherlands, is a popular tourist destination, partly because of its convenient geographical location but also thanks to its long history, artistic treasures and elegant stores. However, the waters have most affected the city's privileged location; the Volcanic Eifel heats the water, which springs from the ground at up to 74 °C in many places. This makes the Aachen thermal springs some of the warmest in Central Europe, and they have been used by both the Celts and Romans. Eventually, these healing springs prompted Emperor Charlemagne to build his palace in Aachen, making it the centre of the great Frankish Empire. The city of Aachen has developed into a technology hub, hosting one of the leading universities of technology in Germany with the RWTH Aachen (Rheinisch-Westfälische Technische Hochschule), the academic hospital Klinikum Aachen, one of the largest medical faculties in Europe, as well as the FH Aachen (Aachen University of Applied Sciences), which is one of the strongest universities of applied sciences in Germany in terms of technology-oriented research.