Louis II, Prince of Monaco
On 26 June 1922, Prince Albert I died in Paris. Louis Grimaldi ascended to the throne as Louis II, Prince of Monaco. While his reign never achieved the grandeur of his father, Louis II left an indelible imprint on the tiny principality. In 1924 the Monaco Football Club was formed and in 1929, the first Grand Prix of Monaco automobile race was held, won by Charles Grover (aka "Williams") driving a Bugatti painted in what would become the famous British racing green color. He collected artefacts belonging to Napoleon I which are now assembled and displayed in the Napoleon Museum attached to the Royal Palace in Monte Carlo.
Rainier III, Prince of Monaco
Rainier III (Rainier Louis Henri Maxence Bertrand Grimaldi; 31 May 1923 – 6 April 2005) ruled the Principality of Monaco for almost 56 years, making him one of the longest ruling monarchs in European history.
Though internationally known for his marriage to American actress Grace Kelly, he was also responsible for reforms to Monaco's constitution and for expanding the principality's economy beyond its traditional casino gambling base. Gambling accounts for only approximately three percent of the nation's annual revenue today; when Rainier ascended the throne in 1949, it accounted for more than 95 percent.