Ancient Library of Alexandria, in Alexandria, Egypt, was the largest and most significant library of the ancient world. It flourished under the patronage of the Ptolemaic dynasty and functioned as a major center of scholarship from its construction in the 3rd century BC until the Roman conquest of Egypt in 30 BC. The library was conceived and opened either during the reign of Ptolemy I Soter (323–283 BC) or during the reign of his son Ptolemy II (283–246 BC).

The library of Alexandria was but one part of the Mausoleum of Alexandria, which functioned as a sort of research institute. In addition to the library, the Museum included rooms for the study of astronomy, anatomy, and even a zoo of exotic animals. The classical thinkers who studied, wrote, and experimented at the museum include the fathers of mathematics, engineering, physiology, geography, and medicine. These included notable thinkers such as Euclid, Archimedes, Eratosthenes,Herophilus, Erasistratus  Hipparchus, Aedesia , Pappus, Hypatia , Aristarchus of Samos, and Saint Catherine.