This ancient airship, the Invincible... We unearthed it from the ground here. It is powered... by the Heart of Babel.
Several years ago, Cid recruited dwarves to help unearth Invincible from the ground below the decommissioned Mobreeze Airship Factory and to refurbish it. As they thought he was great man, they agreed to do so for Cid's sake.
When Rain, Lasswell, Fina and Lid pass through the supposedly-abandoned factory to go to the Wind Shrine, they find the airship and the dwarves working on it. Lid asks one of the dwarves about the ship, but the dwarf says they have never gotten the Invincible off the ground in spite of it being powered by the Heart of Babel—due to its power being sealed by the Wind Crystal. Before they can find out more, the party flees due to the security system, and find out that Evan is working on the airship as well.
The Invincible is not used to freely travel on the world map (due to it being as a series of fixed contact points, with a fixed set of dungeons located in each area, to be freely accessed at any time by spending energy). Rather, it is used for story purposes and, from Season Two onwards, to travel freely between Lapis and Paladia.
The Invincible is a recurring airship name in Final Fantasy games (the first Invincible appeared in Final Fantasy III). The title itself may originate from Stanisław Lem's story The Invincible, where the Invincible is a powerful and armed interstellar space ship.