Azmael's palace

Azmael's palace on Jaconda was a huge citadel, parts of which were more than two thousand years old. Located atop a mountain, centuries of piecemeal development meant that it was lacking in architectural and historical value.

The Doctor, in his fourth incarnation or earlier, once visited the palace and was given a tour by Azmael. This proved to be especially handy given that the interior contained mazes of dark corridors. (PROSE: The Twin Dilemma)

After the Jacondans surrendered to the Gastropods per Azmael's advice, Mestor the Magnificent took control of the palace and resided in its throne room. The Sixth Doctor arrived at the palace in his TARDIS with Peri Brown and Hugo Lang and helped defeat the Gastropods, killing Mestor in the throne room. (TV: The Twin Dilemma)