Zen-Oh's Palace exact location is unknown but it resides above a huge jellyfish that is located in between golden clouds and what appears to be outer space. It is also a separate location from the universes and very far away from them, with even the Angels, as stated by Whis, taking two whole days at full speed to do a one-way trip and four entire days for a single roundtrip, and being more reachable through teleportation, such as the Instantaneous Movement used by the Kais.
The palace where Zen-Oh lives is located on the top of a huge jellyfish and it is in the shape of the kanji "全" that means "all". It also keeps floating. Around the castle there are twelve floating rocks that each has a Universe above them. The inside of the palace is a dark void (brightened by its glowing floor) with thousands of white pillars scattered around the place.