Cassini studied at the Jesuit college in Genoa and then at the abbey of San Fructuoso. He observed at Panzano Observatory between 1648 and 1669 and in 1650, became professor of astronomy at the University of Bologna. Aside from an interest in astronomy, Cassini was also an expert in hydraulics and engineering. He was later employed by the Pope to oversee fortifications and river management on the river Po. In 1669, the senate of Bologna granted him approval to visit Paris under the invitation of Louis XIV, thinking that the trip would be a short one; yet he never returned to Italy. He became director of the Paris Observatory in 1671 and then switched to French citizenship two years later.