Although the economy of Rome is characterised by the absence of heavy industry and it is largely dominated by services, high-technology companies (IT, aerospace, defence, telecommunications), research, construction and commercial activities (especially banking), and the huge development of tourism are very dynamic and extremely important to its economy. Rome's international airport, Fiumicino, is the largest in Italy, and the city hosts the head offices of the vast majority of the major Italian companies, as well as the headquarters of three of the world's 100 largest companies: Enel, Eni, and Telecom Italia.