The University of Strasbourg in Strasbourg, Alsace, France, is the largest university in France, with about 43,000 students and over 4,000 researchers. The present-day French university traces its history to the earlier German language Universität Straßburg, which was founded in 1631, and was divided in the 1970s into three separate institutions: Louis Pasteur University, Marc Bloch University, and Robert Schuman University. On 1 January 2009, the fusion of these three universities recreated a united University of Strasbourg, which is now amongst Europe's best in the League of European Research Universities. The university emerged from a Lutheran humanist German Gymnasium, founded in 1538 by Johannes Sturm in the Free Imperial City of Strassburg. It was transformed to a university in 1621 and elevated to the ranks of a royal university in 1631. The German university still persisted even after the annexation of the City by King Louis XIV in 1681, but mainly turned into a French university during the French Revolution.