The Apollo 4 mission was the first unmanned test flight of the Saturn V rocket, the most powerful rocket ever built. Launched on November 9, 1967, the mission was a major milestone in the Apollo program, and marked the first time a Saturn V rocket was used to launch a spacecraft.
From Wikipedia
Apollo 4, also known as SA-501, was the uncrewed first test flight of the Saturn V launch vehicle, the rocket that eventually took astronauts to the Moon. The space vehicle was assembled in the Vehicle Assembly Building, and was the first to be launched from Kennedy Space Center (KSC) in Florida, ascending from Launch Complex 39, where facilities built especially for the Saturn V had been constructed.