Siegen is a city in Germany, in the south Westphalian part of North Rhine-Westphalia. It is located in the district of Siegen-Wittgenstein in the Arnsberg region. The university town is the district seat, and is ranked as a "higher centre" in the South Westphalian urban agglomeration. In 1975, municipal reforms and amalgamations lifted Siegen's population above the 100,000 mark.