Prince Rainier III of Monaco was the ruler of the Principality of Monaco from 1949 until his death in 2005. He was born on May 31, 1923, and became known for modernizing the small city-state, enhancing its economy through tourism and the casino industry. Rainier was also a key figure in promoting Monaco's international image. In 1956, he married American actress Grace Kelly, which brought significant attention to Monaco. Together, they had three children: Caroline, Albert II, and Stéphanie. Rainier's reign is remembered for his efforts in preserving Monaco's heritage while fostering development and stability in the region.