Isaac, a Jewish merchant, accompanied two ambassadors of Charlemagne to the court of Harun al-Rashid. He returned to Aachen in July 802, bearing an elephant called Abul-Abbas as a gift for the emperor. During the 13th century, many Jews converted to Christianity, as shown in the records of the Aachen Minster (today's Cathedral). In 1486, the Jews of Aachen offered gifts to Maximilian I during his coronation ceremony. In 1629, the Aachen Jewish community was expelled from the city. In 1667, six Jews were allowed to return. Most of the Aachen Jews settled in the nearby town of Burtscheid. On 16 May 1815, the Jewish community of the city offered an homage in its synagogue to the Prussian king, Friedrich Wilhelm III. A Jewish cemetery was acquired in 1822. 1,345 Jews lived in the city in 1933. The synagogue was destroyed during Kristallnacht in 1938. In 1939, after emigration and arrests, 782 Jews remained in the city. After World War II, only 62 Jews lived there. In 2003, 1,434 Jews were living in Aachen. In Jewish texts, the city of Aachen was called Aish or Ash (אש). 21st century The city of Aachen has developed into a technology hub as a by-product of hosting one of the leading universities of technology in Germany with the RWTH Aachen (Rheinisch-Westfälische Technische Hochschule), known especially for mechanical engineering, automotive and manufacturing technology as well as for its research and academic hospital Klinikum Aachen, one of the largest medical facilities in Europe. Geography Aachen is located in the middle of the Meuse–Rhine Euroregion, close to the border tripoint of Germany, the Netherlands, and Belgium. The town of Vaals in the Netherlands lies nearby at about from Aachen's city centre, while the Dutch city of Heerlen and Eupen, the capital of the German-speaking Community of Belgium, are both located about from Aachen city centre. Aachen lies near the head of the open valley of the Wurm (which today flows through the city in canalised form), part of the larger basin of the Meuse, and about north of the High Fens, which form the northern edge of the Eifel uplands of the Rhenish Massif. The maximum dimensions of the city's territory are from north to south, and from east to west. The city limits are long, of which border Belgium and the Netherlands. The highest point in Aachen, located in the far southeast of the city,