Weinheim  is a town in the north west of the state of Baden-Württemberg in Germany with 43,000 inhabitants, approximately 15 km (9 mi) north of Heidelberg and 10 km (6 mi) northeast of Mannheim. Together with these cities, it makes up the Rhine-Neckar triangle. It has the nickname "Zwei-Burgen-Stadt", or Two-Castle city ('Burg' means 'fortress'), named after the two fortresses on the hill overlooking the town in the east on the edge of the Odenwald, the Windeck and the Wachenburg. The city of Weinheim with said Wachenburg castle, built by German Student Corps fraternities in the early 1900s, is the location of the annual convention of the Weinheimer Senioren-Convent.