The Avatar however found out the truth about the retreat in Ultima VII. After joining the Fellowship to infiltrate them, the Avatar was able to enter the retreat. Jan, the groundkeeper, warned him not to enter the caves behind the building. The reason was that the retreat was the location of the Cube Generator, built to protect it. This also was the reason why people heard the Guardian's voice here best.
With the destruction of the generator and the disbanding of the Fellowship, the Meditation Retreat most likely was destroyed like all Fellowship installations.
- The Fellowship doesn't need to be joined. With the Magic Carpet it is easy to just fly over the wall.