How long does it take to make the biggest rocket?

The world's largest rocket was the Saturn V vehicle built by the United States. While design of the rocket, and it's smaller test bed vehicles, the Saturn 1B and Little Joe rockets, commenced in 1961, the actual assembly of a Saturn V vehicle took approximately 18 months. This is from layout of the main fuel tank to transport to the launch pad. well, to make the biggest rocket, it would take the longest time. Be a little more specific please.