A: Paris, Île-de-France, France
In 1257 Robert de Sorbon, a chaplain and confessor to King Louis IX, founded the Collège de Sorbonne, or University of Paris. Starting with 20 theology students, and virtually no library except a small collection of manuscripts, the college quickly built a prodigious reputation as a center for learning, and rapidly expanded its library mainly through donations, including the library of Robert de Douai, physician to Queen Marguerite. In Robert's will dated 1258 he left to the college 1500 pounds Parisian, and bequeathed " 'omnes libros meos de theologia, tam biblias, tam originalia, quam alios libros glosatos' which came to the Sorbonne four years later" (Rouse & Rouse, "The Early Library of the Sorbonne," Authentic Witnesses: Approaches to Medieval Texts and Manuscripts  346).
By the end of the thirteenth century there were as many as twenty thousand foreign students resident in Paris, making Paris the capital of knowledge of the Western world.