Avalon is an island in the Otherworld dimension and home to the Celtic Gods. It is located next to Tír na nÓg.
In ancient times, there were many ways to travel from Earth to Avalon and back, created by powerful men known as the Twelve Walkers. Six of the Twelve Walkers became corrupt and created false paths that would lead travellers to dangerous places or insanity. The actions of these evil Walkers caused a backlash from the human inhabitants of Earth against all magical creatures and many of these creatures followed the paths to relocate to Otherworld. Most of the paths between Earth and Avalon were destroyed and only a few remain.
After the death of King Arthur, his body was taken to Avalon by Merlin. Somehow, the city of Camelot was also taken to Avalon including all of the Knights of the Round Table.
Places of Interest
Kingdom of King Arthur, it was located in Britain, the kingdom existed through most of the 6th Century. Following the fall of Camelot, the kingdom was transported to the other-dimensional realm known as Otherworld by the wizard Merlyn.
In Britain, the wizard Merlin helped King Arthur to establish the kingdom of Camelot, and mentored the Black Knight (Sir Percy of Scandia) to oppose the evil influence of Arthur's illegitimate son, the knight Mordred. In the end, Mordred and Morgan le Fay brought down Camelot, but were killed themselves in the process. (All of these people would later manifest, in various ways, in the present.)
Iron Man and Doctor Doom were present at that time, following a battle and the treason of an employee of Doom. Iron Man allied himself with Arthur, and Doom with Morgan, but the two time travelers were eventually forced to work together to return to the present.
At some point prior to the fall of Camelot, Modred the Mystic (no relation to Mordred) was approached by Merlin (or an impostor) to study magic in Camelot. Modred was instead corrupted by the power of the Darkhold, and would lose his soul and his love but would gain near-immortality and a mastery of magic. He would battle Chthon and the Darkholders through the modern day, but would bear a deadly vendetta against Merlin and his allies.
Merlyn wanted to Tommy Tyme a lesson about magic, the wizard tripped the boy, activating his Clock of the Ages and sending him back in time to England in the 6th century. There Tommy assisted Merlin in rescuing the captured King Arthur from the evil Black Knight. When Tommy returned to his own time he had learned a greater appreciation and belief in magic.
In the 6th Century Sersi also assisted Merlin.
History of location is unknown.
The Starlight Citadel's history is unknown but it currently exists in Otherworld and is the home of the Omniversal guardian and current headquarters of the Dimensional Development Court.
Stonehenge iw n ancient stone circle and center of mystical power located in Amesbury, England, at the Salisbury Plain in the county of Wiltshire.
According to Umar, The Ancient One once humbled Dormammu there "in the dim, half-forgotten past".
It was also seemingly a launching pad for Kree Eternal Demon Druid/Ard-Con, used by his followers as a temple.
In recent times, Umar invaded Earth and the Ancient One brought her to Stonehenge to duel him without threatening innocent lives. Once in Stonehenge, the Ancient One and his disciple Dr. Strange brought the powerful monster Zom, who scared Umar away to her own Dark Dimension. Zom then turned against the Ancient One and Dr. Strange, and the Ancient One willingly surrendered his power, melting with the local menhirs, to give Strange a chance to win the fight. By cutting off Zom's mystic topknot, per the Ancient One's counsel, Strange attracted the attention of the Living Tribunal, who banished Zom and in turn sentenced Earth to destruction, to prevent an evil wizardy plague from expanding. Strange demonstrated his skill and convinced the Tribunal to give him a chance to solve the situation. The Tribunal laid the huge Glass of Doom in Stonehenge, and both him and Strange left. Once the Tribunal was satisfied with Strange's resolution of the events, the Ancient One reappeared, explaining that he had willingly accepted that prison to increase Strange's power so that Strange could defeat Zom, and that he could shatter his own binding spell once the cosmic balance had been restored.
Ard-Con later freed from his imprisonment and rampaged through England to use Stonehenge and depart Earth.
As ordered by his ancestor, the Black Knight came to Stonehenge in order to destroy his ebony blade through magical means. Here, he was confronted by an old woman who suddenly transported him to Polemachus to find an enchanted well to destroy his sword. The Black Knight and Aragorn reappeared by the end of the night and returned to Garrett Castle.