Prince Rainier III 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 tiny nation, transforming it into a thriving tourist destination and financial center. His reign saw significant developments in infrastructure and the economy. Rainier III is also famous for his marriage to American actress Grace Kelly in 1956, which brought international attention to Monaco. Together, they had three children: Caroline, Albert, and Stephanie. His legacy includes a commitment to preserving the cultural heritage of Monaco while promoting its growth.