Xindi Council planet

From Memory Alpha, the free Star Trek reference.

The Xindi Council planet is the home to the Xindi Council. Its location is top-secret, and the planet is located inside a security zone.

The Council chambers are located in a fortress built into a mountainside by the Xindi-Avians some 4,000 years ago. The fortress is two kilometers above ground level and prefectly concealed by the cloud layer that surrounds it. The only way in is through the air.

After the Xindi superweapon's location on Azati Prime was discovered by the Humans, it was moved to the Council planet. It was located in a large underground facility in a rocky portion of the planet. (ENT: "The Council")