The Catholic University of Leuven (in Dutch, Katholieke Universiteit Leuven or K.U.Leuven), the largest Flemish university, is located in the historic town of Leuven in Flanders, the Dutch-speaking (northern) part of Belgium. It was founded in 1425 and is now the oldest Catholic university in the world still in existence.

With the steady rise to renewed prominence of the Dutch language, the then-bilingual University was eventually split in 1968 into two new universities. The French-speaking Université Catholique de Louvain moved to a newly built campus in Louvain-la-Neuve in Wallonia, Belgium. The Dutch-speaking Katholieke Universiteit Leuven remained in Leuven.

One European survey ranks K.U.Leuven among the top ten European universities in terms of its scientific output.

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