Italy per 1,000 people) and 4,015,000 goods vehicles circulated on the national road network. The national railway network, state-owned and operated by Rete Ferroviaria Italiana, in 2008 totalled of which is electrified, and on which 4,802 locomotives and railcars run. The national inland waterways network comprised of navigable rivers and channels in 2002. In 2004 there were approximately 30 main airports, including the two hubs of Malpensa International in Milan and Leonardo da Vinci International in Rome, and 43 major seaports, including the seaport of Genoa, the country's largest and second largest in the Mediterranean Sea. In 2005 Italy maintained a
Italy in the Middle Ages the invasion of the South, part of a 12th-century Byzantine effort to regain the influence it had held on the peninsula during the reign of Justinian. In the 11th century, the Normans occupied the Lombard and Byzantine possessions in Southern Italy, ending the six century old presence of both powers in the peninsula. The independent city-states were also subdued. During the same century, the Normans also ended Muslim rule in Sicily. Norman rule in what had once been Byzantine territory naturally angered Byzantium, which in 1155 made a last attempt under the Emperor Manuel I Komnenos to reassert its authority