RWTH Aachen University (Rheinisch-Westfälische Technische Hochschule Aachen) is a public research university in Aachen, in the German state of North Rhine-Westphalia. Founded in 1870, it ranks among Germany's oldest and most prominent technical universities and is a founding member of the TU9 alliance of leading German institutes of technology. With roughly 47,000 students, it is also one of the largest universities in the country.

The institution opened in October 1870 as the Royal Rhenish-Westphalian Polytechnic School (Königliche Rheinisch-Westfälische Polytechnische Schule) in what was then the Kingdom of Prussia, with a founding emphasis on engineering and the applied sciences. Over more than 150 years it grew into a comprehensive technical university while retaining its strong roots in engineering education and industrial research.

Today RWTH Aachen is organized into ten faculties and around 290 institutes, covering engineering, the natural sciences, medicine, economics, and the humanities. It is recognized under Germany's national Excellence Strategy as one of the country's elite research universities, and it maintains close partnerships with industry and with major research organizations. The university operates its own teaching hospital, the Uniklinik RWTH Aachen, one of the largest medical centers in Europe.

Located in the far west of Germany, Aachen sits within the tri-country region where Germany meets Belgium and the Netherlands, giving the university a strongly international and cross-border character. RWTH Aachen hosts a large community of international students and researchers, supports a broad network of exchange partnerships, and offers a range of English-taught master's programmes. Its campus culture combines a demanding academic environment with an active student community shaped by the wider Euregio setting.