Milennia before the series began, Bardos was once where gigantic cyborg aliens used as a base for operations. The humans worshipped the aliens as Gods, one of them Zeus took an interest in them, breaking ties from his original home. Hades plotted to rebel against Zeus for control of the island, but in a failed assassination attempt had his body destroyed. Hades came back as the flaming entity Emperor of Darkness and sunk the island under tides with his power.
When Bardos resurfaced due to tidal changes, the island was found by a team composed of Dr. Hell, Tsubasa Nishikiori, Juzo and Kenzo Kabuto, along with Tetsuya Tsurugi. On the island, were the ancient but advanced technology of the Mycenae Empire. Dr. Hell revealed his intentions of world domination, but Tsubasa knew about this and used explosives set around the island to blow up Bardos.
However, Dr. Hell survived and remade Bardos into his personal image. For most of the series, Bardos would be seen as Dr. Hell would make his move. At times, members of the Mycenae Empire such as Archduke Gorgon attempted to reclaim the island but were stopped. Dr. Hell then had the island move towards Japan for a final assault on the Photon Power Laboratory, until he was killed and the Mycenae Empire came up from below the island.
Bardos contains a laboratory used by a Kedora-controlled Kenzo Kabuto to produce the Mechanical Beasts and other mechanical soldiers. It also features a docking area for the mobile fortresses. It is also capable of movement across the ocean.