The Gigan Mountains are a mountain range that contain a hidden temple. Within was the long-hidden Key to Babylon Garden. Using a book from the library of Soleanna, the Babylon Rogues located the hidden chamber; however, removing the Key from its pedestal activated the chamber's guardian, Angelus, who delivered a warning against removing the key. While dangerous, the guardian turned out to be an elaborate hologram of sorts, and the Rogues disabled it by destroying projectors set around the chamber. The tunnel to the chamber later collapsed, and the Rogues were then chased by the Battle Bird Armada across the mountain range. (SU: #33, #34)
- This mountain range is based on the stages Gigan Rocks and Gigan Device from Sonic Riders: Zero Gravity.