4. Italian Grand Prix - 1961
Over half a century ago, safety was a very abstract concept in Formula 1, a minor concern brushed aside even as fiery deaths occurred with unnerving regularity.
The 1961 Italian Grand Prix at Monza was the scene of Formula 1's greatest tragedy.
The race for the world title came down to just two drivers, Phil Hill and Wolfgang von Trips, who were also team mates at Ferrari.
On race day, Hill led the way at the start, but disaster struck on the second lap when von Trips fatally collided with Jim Clark's Lotus.
The two cars touched wheels; the Ferrari careered towards an embankment and plunged into the crowd before tumbling back onto the track in a fury of disintegrating metal. Von Trips and 14 unfortunate spectators perished.
A grief-stricken Phil Hill became America's first F1 world champion.