Originally, the islet was called Panorm, and in 298 BC it was noticed by Demetrius (Demetrios) Poliorcetes, the son of one of Alexander the Great’s generals, Antigonus I Monophthalmus. In the struggle against Lysimachus of Thrace and Cassander of Macedon, Demetrius built a fortress on this islet to establish a foothold on the Sea of Marmara, and he named the island Antigonus in honor of his father.

From 823 to 829, the Patriarch of Constantinople, Methodius, languished in captivity on Antigonus. The most vivid and dramatic chapters in the history of the Princes’ Islands are probably connected with the stay here of two disgraced patriarchs – Patriarch Methodius of Constantinople, and later his successor, Patriarch Ignatius. Hagiographic texts vividly recount that the future Patriarch Methodius was imprisoned in an underground dungeon from late 823 until spring 829: “The Emperor [Michael II the Amorian] ordered the blessed one to be scourged with oxhide thongs across his face, then confined him in a narrow grave-like cell with a small opening through which meager food was lowered. Two criminals were imprisoned with him underground, and outside there was an unceasing guard. After a short time, these two died, unable to endure the stench and darkness of the underground crypt, as well as the unbearable voracity of lice. Only this noble and supernaturally resilient man – Methodius – survived. Who else could have endured the hordes of mice that infested the dead bodies and tormented the man of God buried alive? This stubborn man lost all the hair on his head after spending five years in this dreadful prison.” However, according to another version, only one of the criminals died, and Methodius had the spiritual strength to bring the other to repentance. The text does not clarify why the patriarch, known for his righteous life, and two criminals received equally harsh punishment. Legal documents of that era also do not prescribe strict imprisonment as a penalty for any specific crimes. Therefore, it is doubtful that the patriarch and ordinary criminals would have been placed in the same cell. Nevertheless, it is quite possible that the author of the hagiography used standard clichés here, perhaps somewhat exaggerating the horrors of imprisonment to highlight the martyr’s crown of the ascetic. Other sources portray Methodius’s imprisonment conditions somewhat differently. It is reported, in particular, that his comrades in the struggle for icons, Theodore and Theophanes, “delivered a letter to him through a faithful man, a fisherman who served Saint Methodius in his simple needs. Due to the darkness of his crypt, he brought him lamp oil every Saturday for one coin, which was enough to light the prisoners for the week. Once the fisherman fell ill and did not bring his usual portion of oil, but by the saint’s prayer, God replenished the shortage.” In any case, it is known that the holy confessing monks Theodore and Theophanes the Branded sent Saint Methodius a greeting in verse, and the prisoner, while confined in the underground (“locked in a tomb-like cave”), also responded with a poetic greeting. After many years of imprisonment on Antigonus, during the regency of Empress Theodora, Methodius was released and became patriarch. As the Continuator of Theophanes reports, “he who preserved virtue inviolate through numerous labors and feats, who lost his hair due to prolonged imprisonment in rot and filth, but by God and Empress Theodora received governance and authority over the church. And this was the great Methodius – an invincible zealot of the church.”

Thus, exile and confinement in a crypt on the islands did not prevent him not only from surviving but also from maintaining relations with his comrades, writing poetic messages, and even returning to active political activity. 

In 842, by order of the same Theophilos, Methodius was released from his prison allegedly to clarify certain points in the Holy Scriptures, which the reigning Patriarch John VII was unable to do. In 843, Methodius was again elected patriarch.