Museo Galileo library is located in the historical centre of Florence. It is mainly used by scholars and researchers in the history of science, but it is also open to those Museum visitors who, after their tour, would like to learn more about what they have appreciated during their visit. Among the many services is the online collective database (ca. 300,000 bibliographical records), that can be used to search for books, manuscript and archival materials, historical and modern digital photos. Over 15,000 documents are freely available in digital version.