The title of this article is ambiguous. For other meanings, see Aachen (disambiguation).

Aachen [Zum Anhören bitte klicken!Abspielenˈaːxn̩] (Öcher Platt: Oche; French Aix-la-Chapelle [ɛkslaʃaˈpɛl]; Dutch Aken; Latin Aquæ Granni) is an independent large city in the North Rhine-Westphalian administrative district of Cologne. The former imperial city is a member of the Landschaftsverband Rheinland (Regional Association of the Rhineland) and, according to the Aachen Act with effect from 21 October 2009, the administrative seat of the Städteregion Aachen. In 1890 Aachen exceeded the population of 100,000 for the first time and since then has been the westernmost major German city. Aachen borders on the Netherlands and Belgium.

With the Rhenish-Westphalian Technical University (RWTH), funded since 2007 as part of the Excellence Initiative, Aachen has one of the largest and most traditional technical universities in Europe, along with other institutions of higher education. The city's landmark, Aachen Cathedral, dates back to the Palatine Chapel of the Aachen Royal Palatinate founded by Charlemagne, which is considered a masterpiece of Carolingian architecture. Together with the cathedral treasury, the cathedral was added to the UNESCO World Heritage List in 1978 as the first German and second cultural monument in the world. The city is the episcopal see of the Aachen diocese and the venue of the annual CHIO Aachen equestrian tournament. Furthermore, it is an important location for the German confectionery industry, in particular due to the Aachener Printen, a local speciality.

Due to the border location "in the heart of Europe", there are numerous cultural, especially architectural influences from the neighbouring regions, the Belgian-Dutch area. It is probably not least because of this European character - Charlemagne, who made Aachen the political, cultural and spiritual centre of his empire, was called Pater Europae ("Father of Europe") during his lifetime - that the International Charlemagne Prize has been awarded here annually since 1950 to personalities from Germany and abroad for services to the European unification process.

Aachen is a state-recognised spa for the spa areas of Monheimsallee and Burtscheid with their rich thermal springs. The name Bad Aachen is occasionally used in the city's tourism advertising; however, the city has never applied to include the predicate Bad in its official name.