a Grand Prix lap of , in use until 1954. The outbreak of World War II meant racing at the track was suspended until 1948 and parts of the circuit degraded due to the lack of maintenance and military use. Monza was renovated over a period of two months at the beginning of 1948 and a Grand Prix was held on 17 October 1948. High speed oval In 1954, work began to entirely revamp the circuit, resulting in a course, and a new high-speed oval with banked sopraelevata curves (the southern one was moved slightly north). The two circuits could be combined to re-create the former long circuit, with cars running parallel on the main straight. The first Lesmo curve was modified to be made faster, and the track infrastructure and facilities were also updated and improved to better accommodate the teams and spectators. The Automobile Club of Italy held Race of Two Worlds exhibition competitions, intended to pit United States Auto Club IndyCars against European Formula One and sports cars. The races were held on the oval at the end of June in 1957 and 1958, with three 63 lap heat races each year, races which colloquially became known as the Monzanapolis series. Concerns were raised among the European drivers that flat-out racing on the banking would be too dangerous, so ultimately only Ecurie Ecosse and Maserati represented European racing at the first running. The American teams had brought special Firestone tyres with them, reinforced to withstand high-speed running on the bumpy Monza surface, but the Maseratis' steering was badly affected by the larger-than-usual tyre size, leading to the Modena-based team withdrawal. Ecurie Ecosse's three Jaguar D-type sports cars used their Le Mans-specification tyres with no ill-effects, but since they raced at less than their practice speeds to conserve their tyres, they were completely out paced. Two heats in 1957 were won by Jimmy Bryan in his Kuzma-Offenhauser Dean Van Lines Special, and the last by Troy Ruttman in the Watson-Offenhauser John Zink Special. In 1958 Jaguar, Ferrari and Maserati teams appeared alongside the Indy roadsters, but once again the American cars dominated the event and Jim Rathmann won the three races in a Watson-Offenhauser car. Formula One used the high speed track in the 1955, 1956, 1960 and 1961 Grands Prix. Stirling Moss and Phil Hill both won twice in this period, with Hill's win at Monza making