Appears In: M4R
The Main Palace is built of floating rocks and green crystals, and reaches from above the two cloud layers of Spire to below them. The Palace is given its name not because it is an actual man-made palace, but because it appears to be man-made. It as actually written by Atrus to look man-made to trick greedy explorers into linking there without any means of linking out.
Sirrus was trapped there for twenty years and survived by eating the unusual vegetables that grow between the cloud layers. He built a Rock Ship using the floating rocks and maintained it using crystals for electromagnets. Also on the Main Palace is Sirrus's organ, Spider Throne, and Bomb Factory.