The Complutense University of Madrid is a public research university located in Madrid. Founded in Alcalá in 1293, it is one of the oldest operating universities in the world. It is located on a sprawling campus that occupies the entirety of the Ciudad Universitaria district of Madrid, with annexes in the district of Somosaguas in the neighboring city of Pozuelo de Alarcón. It is named after the ancient Roman settlement of Complutum, now an archeological site in Alcalá de Henares, just east of Madrid.

Madrid is the capital and most populous city of Spain. The city has almost 3.4 million inhabitants and a metropolitan area population of approximately 7 million. It is the second-largest city in the European Union (EU), and its monocentric metropolitan area is the second-largest in the EU. The municipality covers 604.3 km2 (233.3 sq mi) geographical area. Madrid lies on the River Manzanares in the central part of the Iberian Peninsula at about 650 meters above mean sea level. The capital city of both Spain and the surrounding autonomous community of Madrid, it is also the political, economic, and cultural centre of the country. The climate of Madrid features hot summers and cool winters.