In 1927, Belgrade's first airport opened, and in 1929, its first radio station began broadcasting. The Pančevo Bridge, which crosses the Danube, was opened in 1935, while King Alexander Bridge over the Sava was opened in 1934. On 3 September 1939 the first Belgrade Grand Prix, the last Grand Prix motor racing race before the outbreak of World War II, was held around the Belgrade Fortress and was followed by 80,000 spectators. The winner was Tazio Nuvolari.