One of the world's chief depositories of books. The foundation of this famous collection was begun by Pope Martin V (reigned 1417-31), but Pope Nicholas V (reigned 1447-55) is considered its real founder. He acquired the imperial library of Constantinople, scattered by the Turks, and donated it to the Vatican. Pope Sixtus IV (reigned 1471-84) officially established the modern Vatican Library in 1475, and Pope SIxtus V (reigned 1585-90) ordered the construction of new buildings that are still in use. The library is administered by a prefect, writers work on scientifically cataloguing the manuscripts, and assistants catalogue the printed books. The library maintains mauscript repairing, bookbinding and publishing departments, and as a scientifice institution for the use of students, it is presently making one of the greatest contributions to human thought.