High Quality Content by WIKIPEDIA articles! The 1966 Monaco Grand Prix was a Formula One motor race held at the Circuit de Monaco on May 22, 1966. It was the opening round of the 1966 Formula One season, the first of a new era for Formula One, the `return to power` as engine regulations were altered from 1.5 litres of maximum engine displacement to 3.0 litres. It was the 24th Monaco Grand Prix.