One Piece Chapter 4, page 11-13: Chapter 4: The Great Captain Morgan

Morgan boasts about how he labored to achieve his rank through his own strength, declaring that rank means everything and therefore everything he does is right. The terrified Marines quickly agree, shouting praises. Morgan then orders them to raise his giant statue to the highest point of the fortress as a monument to his power and greatness.

Luffy wanders around the base, noting how quiet it is and wondering where everyone is. On the roof, the Marines are straining to pull up Morgan's statue. The statue bumps against the building with a loud "KLUNK," infuriating Morgan, who demands to know if they were careless. Hearing voices from above, Luffy decides to climb up and check it out.

Luffy grabs onto a high ledge of the fortress, stretching his rubber arms back. With a massive grin, he launches himself upward using his "Gum-Gum Rocket" technique, flying high into the air toward the roof.