Palace of Blackthorn

Castle Blackthorn was a horrible place from whence Lord Blackthorn ruled over Britannia, full of foul creatures, members of the Oppression and traps. The castle itself was intentionally built as a maze to confuse intruders..

It was built on the newly emerged volcanic island of Terfin after Blackthorn was manipulated by the Shadowlords. Interestingly, the position of the castle in the middle between the three volcanoes corresponds with the location where the Avatar retrieved the Skull of Mondain from the seabed in Ultima IV, indicating an evil spot.

The Avatar entered it in Ultima V, to retrieve the Crown. After the end of the dictatorship, the castle was left to rot. But not for long, as the mage Sutek made it his home, to conduct his experiments in peace. The Avatar met him in Ultima VI, as he/she passed through the castle, to find the balloonist with his plans. Shortly later, Sutek accidentally turned himself to stone when fighting against some warriors. His statue was dumped into the sea, and the castle torched.

The Gargoyles used the stone to erect their own city, and so the ruin had vanished by the time of Ultima VII, ending its history.

Trivia

 * Entering the castle without the Black Badge in Ultima V was a really bad idea...
 * Batlin still describes the ruins in The Book of Fellowship, which was written some years prior to Ultima VII, giving a rough timescale, when the ruins vanished.