Opened in 2010, the Museo Galileo occupies the historic Palazzo Castellani, former home of the Museum of the History of Science since 1930. The Museo Galileo is home to the only surviving instruments designed and built by Galileo himself. The most important are two original telescopes and the objective lens of the telescope with which Galileo discovered Jupiter’s moons. The collection of the Museum includes around 5000 original items, divided into two fundamental categories: the apparatus and scientific instruments of the Medici and the Lorraine collection of instruments and didactic and experimental devices. The Istituto carries out important research programs and possesses a remarkable library with a large collection of both older and modern books and periodicals, mostly devoted to the history of science.