Rainier III, Prince of Monaco, was born on May 31, 1923, and ruled from 1949 until his death in 2005. He was the son of Prince Pierre of Monaco and Princess Charlotte, Duchess of Valentinois. Rainier is known for modernizing the principality and promoting tourism, which significantly boosted Monaco's economy. During his reign, Rainier III married American actress Grace Kelly in 1956, which brought international attention to Monaco. The couple had three children: Caroline, Princess of Hanover, Albert II, Prince of Monaco, and Stéphanie, Princess of Monaco. Rainier's legacy includes the establishment of the Monaco Grand Prix and the Monte Carlo Casino.