...No. Who told you that?
Hollow Bastion - Kingdom Hearts Wiki - A world of information not accessible by Gummiship
And I quote:
Not based on a Disney film, though showing Disney influence, Hollow Bastion is a colossal castle that towers above the rest of its world, Radiant Garden. At one point, it was the only remaining part of the world, along with the waterways beneath it. Because of this, the world itself was known as "Hollow Bastion" in Kingdom Hearts, Kingdom Hearts: Chain of Memories, and most of Kingdom Hearts II. However, it regains its original name of Radiant Garden by the end of Kingdom Hearts II, when Tron used his powers to show what the world was like before it's destruction.