Editing Monza Circuit (section)

===High speed oval===
In 1954, work began to entirely revamp the circuit, resulting in a {{cvt|5.750|km|mi|abbr=on}} course, and a new {{cvt|4.250|km|mi|abbr=on}} high-speed oval with banked ''sopraelevata'' curves (the southern one was moved slightly north).<ref name=F1.comHistory/><ref name=MonzaNet1955>{{cite web |title=1955–1971: Construction of the high speed track and other important works |url=http://www.monzanet.it/eng/storia_1955_71.aspx |archive-url=https://web.archive.org/web/20080415212806/http://www.monzanet.it/eng/storia_1955_71.aspx |publisher=MonzaNet.it |work=Autodromo Nazionale Monza |year=2007 |archive-date=15 April 2008 |access-date=17 September 2009 |url-status=dead}}</ref> The two circuits could be combined to re-create the former {{convert|10|km|3}}<ref name=F1.comHistory/> 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.<ref name=F1db/><ref name=MonzaNet1955/>

The [[Automobile Club of Italy]] held {{cvt|500|mi|km|abbr=on}} [[Race of Two Worlds]] exhibition competitions, intended to pit [[United States Auto Club]] [[American Championship Car Racing|IndyCar]]s against European Formula One and sports cars.<ref name=F1.comHistory/><ref name=MonzaNet1955/> The races were held on the oval at the end of June in 1957 and 1958,<ref name=ChampCarStats>{{cite web |title=Autodromo Nazionale Monza |url=http://www.champcarstats.com/tracks/monza.htm |publisher=ChampCarStats.com |year=2009 |access-date=17 September 2009}}</ref> with three 63 lap<ref name=ChampCarStats58H1>{{cite web |title=1958 500 Miglia di Monza Heat 1 |url=http://www.champcarstats.com/races/1958nc1.htm |publisher=ChampCarStats.com |year=2009 |access-date=17 September 2009}}</ref> {{convert|267.67|km|2}} heat races each year, races which colloquially became known as the ''Monzanapolis'' series.<ref name=ChampCarStats/><ref name="About Milan">{{cite web |title=History of Monza GP |url=http://www.aboutmilan.com/history-of-monza-track.html |archive-url= https://web.archive.org/web/20101012182849/http://www.aboutmilan.com/history-of-monza-track.html |publisher=About Milan |archive-date=12 October 2010 |access-date=8 October 2010 |url-status=live}}</ref> Concerns were raised among the European drivers that flat-out racing on the banking would be too dangerous,<ref name="About Milan"/> so ultimately only [[Ecurie Ecosse]] and [[Maserati]] represented European racing at the first running.<ref name=ChampCarStats57H1>{{cite web |title=1957 500 Miglia di Monza Heat 1 |url=http://www.champcarstats.com/races/1957nc1.htm |archive-url= https://web.archive.org/web/20091013101855/http://www.champcarstats.com/races/1957nc1.htm |publisher=ChampCarStats.com |year=2009 |archive-date= 13 October 2009 |access-date=17 September 2009 |url-status=live}}</ref> The American teams had brought special [[Firestone Tire and Rubber Company|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.<ref name=ChampCarStats57H1/>

Ecurie Ecosse's three [[Jaguar D-type]] sports cars used their [[24 Hours of Le Mans|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 outpaced. Two heats in 1957 were won by [[Jimmy Bryan]] in his [[Kuzma (constructor)|Kuzma]]-[[Offenhauser]] ''Dean Van Lines Special'',<ref name=ChampCarStats57H1/><ref name="ChampCarStats57H2">{{cite web|title=500 Miglia di Monza Heat 2|url=http://www.champcarstats.com/races/1957nc2.htm|publisher=ChampCarStats.com|access-date=23 November 2010}}</ref> and the last by [[Troy Ruttman]] in the [[A. J. Watson|Watson]]-[[Offenhauser]] ''John Zink Special''.<ref name=ChampCarStats57H3>{{cite web|title=500 Miglia di Monza Heat 3|url=http://www.champcarstats.com/races/1958nc3.htm|publisher=ChampCarStats.com|access-date=23 November 2010}}</ref> In 1958 [[Jaguar Cars|Jaguar]], [[Ferrari]] and Maserati teams appeared alongside the Indy roadsters,<ref name=MonzaNet1955/><ref name=ChampCarStats58H2>{{cite web|url=http://www.champcarstats.com/races/1958nc2.htm|title=1958 500 Miglia di Monza Heat 2|publisher=ChampCarStats.com|year=2009|access-date=17 September 2009}}</ref> but once again the American cars dominated the event and [[Jim Rathmann (race car driver)|Jim Rathmann]] won the three races in a [[A. J. Watson|Watson]]-[[Offenhauser]] car.<ref name=ChampCarStats/>

Formula One used the {{cvt|10.000|km|mi|abbr=on}} high speed track in the [[1955 Italian Grand Prix|1955]], [[1956 Italian Grand Prix|1956]], [[1960 Italian Grand Prix|1960]] and [[1961 Italian Grand Prix|1961]] Grands Prix.<ref name=F1.comHistory/><ref name=MonzaNet1955/> [[Stirling Moss]] and [[Phil Hill]] both won twice in this period, with Hill's win at Monza making him the first American to win a Formula One race. The combined circuit was not used for 3 years because during the 1956 event the Ferraris and Maseratis were suffering mechanically on the banking, and the combined circuit was used again in 1960 because Ferrari's main strength that year was straight-line speed and the organizers wanted to maximise this advantage.<ref name="History F1" /> The 1961 race saw the death of [[Wolfgang von Trips]] and fifteen spectators when a collision with [[Jim Clark]]'s [[Team Lotus|Lotus]] sent von Trips' car airborne and into the barriers at the approach to the Parabolica.<ref name=F1db/><ref name="History F1">{{cite web|title=A history of the Italian Grand Prix|url=http://www.formula1.com/news/features/2004/9/2159.html|work=Formula1.com|publisher=Formula One Administration Ltd.|access-date=23 November 2010|date=8 September 2004}}</ref>

Although the accident did not occur on the oval section of the track, the high speeds were deemed unsafe and F1 use of the oval was ended. Another attempt was made to use the combined circuit for the 1963 race, but the extremely bumpy nature and poor overall quality of the concrete banking saw some cars suffer mechanically. The teams protested and threatened to leave unless only the road circuit was used, which is ultimately what happened.<ref name="Banking F1">{{cite web|title=The hidden history of the Monza banking|url=http://www.formula1.com/news/features/2005/8/3500.html|work=Formula1.com|publisher=[[Formula One Group|Formula One Administration Ltd.]]|access-date=23 November 2010|date=30 August 2005}}</ref> Future Grands Prix were held on the shorter road circuit,<ref name=MonzaNet1955/> with the banking appearing one last time in the film ''[[Grand Prix (1966 film)|Grand Prix]]''.<ref name="Banking F1" /> New safety walls, rails and fences were added before the next race and the refuelling area was moved further from the track. Chicanes were added before both bankings in 1966, and another fatality in the 1968 1000&nbsp;km Monza race led to run-off areas added to the curves, with the track layout changing the next year to incorporate permanent chicanes before the banked curves – extending the track length by {{convert|100|m|yd|abbr=on}}.<ref name=MonzaNet1955/>

The combined circuit held its last major race in 1969 with the 1000&nbsp;km of Monza, the event moving solely to the road circuit the next year; the banking has never been used again for any major races.<ref name=MonzaNet1955/> The banking still exists, albeit in a decayed state in the years since the last race, escaping demolition in the 1990s. It is used once a year for the Monza Rally, which served part of the [[2021 World Rally Championship]], which was the first FIA championship event since 1969.<ref name="Banking F1" /> The banked oval was used several times for record breaking until the late 1960s, although the severe bumping was a major suspension and tyre test for the production cars attempting endurance records, such as the [[Ford Corsair]] GT which in 1964 captured 13 records.<ref>Monza year Book 1965.</ref>