The Ghost Tower is an air traffic control tower that was originally intended to be located at Fort Baxter Air Base. During the game's initial development, Fort Baxter Air Base had its own runway and control tower. Sometime during development, the tower and runway were removed, likely due to the nearby airport's runway being huge, therefore dwarfing the military runway. However, the game developers forgot to remove the LOD texture of the tower.
The tower was removed from the game before its release, but the player can still see the leftover LOD texture of the tower. The tower's LOD texture can be seen before entering the mainland, but it will disappear after the mainland is entered, because when the player enters it, the map fully loads and the LOD texture cannot be seen. Strangely, the Ghost Tower also appears in GTA Vice City Stories as well. This is possibly, because of GTA Vice City's map being recycled for GTA Vice City Stories.