Dark Tower

The Dark Tower looms over the northwestern point of the ruined city of Skara Brae in Ultima VII, an ominous testament to the powers of its liche lord, Horance.

History
Following the events of Ultima VI, the seclusive mage Horance—already well under the grip of insanity from years of isolation—had the Dark Tower constructed upon the site of his humble dwelling on Iver's Rounding, now fully joined with mainland Skara Brae. Within the tower, Horance's pursuit of the secret of immortality came to fruition by his becoming one with a power-hungry liche, and the keep withstood the great fire that ravaged Skara Brae as the consequence of an ill-fated attempt by its citizens to put an end to the necromage's malevolent endeavors.

By the time of Ultima VII, the tower's walls had been infused with blackrock to shield it from disturbances in the ether caused by the Guardian's Tetrahedron Generator. Central to this sinister construct was the Well of Souls, where Horance kept the souls of the dead incarcerated, drawing upon them to further his dark powers. Every midnight, the ghostly inhabitants of Skara Brae were drawn to the tower against their will to be fed upon by the liche lord, while undead creatures guarded his domain.

The tower became devoid of its hold over Skara Brae when the Avatar vanquished both the liche and the Well of Souls. An exorcised Horance remained there, however, vowing to rebuild the city of Spirituality to its former standing.

Trivia

 * Despite the tower being built partly of blackrock, Rudyom's Wand has no destructive effect.
 * Under Bob White's tenure as lead designer of Ultima IX, the Dark Tower was due to make an appearance in the game—including records of Horance's occupation therein—with the inert Well of Souls standing as the entrance to a dungeon known as the Catacombs of the Angry Dead.