Created approximately around 300 BCE, the Great Library of Alexandria stands as a monument to ancient academic achievement. Funded by Ptolemy I, the library at Alexandria housed around 500,000 volumes- no small feat by any day's standard. One factor in the vastness of the library is Alexandria's location; as a center of trade, it allowed the accumulation of massive amount of information on different cultures.
The Library was home to many of the classical thinkers we associate with antiquity, such as Archimedes, Heophilus, Euclid, and Eratosthenes. These people who were associated with the library are many of the developers of the fields we have come to associate with astronomy, medicine, mathmatics, mechanics, etc.
The Great Library of Alexandria was in itself a learning tool as well as being a storage of the accumulated information. Much of what we know today in geometry and medicine result from the information these librarians of the Alexandrian Age amassed. Moreover, the Library preserved information during the years of the European 'Dark Ages,' preserving the texts of classical Greek philosophers as well as retaining information advancements for progeny.
Further information:
http://www.perseus.tufts.edu/GreekScience/Students/Ellen/Museum.html