Io Castle
Io Castle (イオ・キャッスル) orbited the planet Jupiter, and in the manga and Sailor Moon Crystal, it was the palace of Princess Jupiter, given to her by Queen Serenity when she was born.
In Act 48 of the manga and in Sailor Moon Eternal, the Solar System Sailor Princesses called upon the power of their castles and directed it to the Holy Grail, which gave Super Sailor Moon the power to transform into Eternal Sailor Moon.
