The Structure of the Walls
From the Porta Phani eastwards to Petri Kapoussi, the next city gate, the fortifications of Constantinople formed a particularly interesting section of the Harbour Walls. In this area, there were two lines of walls enclosing a large triangular territory. The inner wall curved deeply inward along the steep northern slope of the Fifth Hill, creating a strong defensive enclosure.
This fortified space was known as the Castron of the Petrion (Κάστρον τοῦ Πετρίου), meaning “the Fortress of Petrion.” It was named after Petrus, the Master of the Offices during the reign of Emperor Justinian the Great in the sixth century. The surrounding district itself was called the Petrion (Πέτριον, Regio Petri Patricii), meaning “the Region of Peter the Patrician.”
It is important not to confuse the Petrion with the district of Petra (Πέτρα), which lay at Kesme Kaya, above Balat Kapoussi, on another part of the city’s northern shore Turkey Private Tours.
The Gates and Entrances of the Petrion
At the western side of this enclosure, just to the west of Porta Phani, stood a small inner gate called the Diplophanarion. This gate connected the Castron of the Petrion with the interior of the city, providing a passage between the double walls.
The main entrance at the eastern end of the Castron was the Petri Kapoussi, located in the outer wall. This gate led directly to the street running along the shore of the Golden Horn. Interestingly, it still retains the ancient name of the district, showing a rare case of continuity from Byzantine to Ottoman times Gate St. John Forerunner Baptist.
The German scholar Dr. Mordtmann identified Petri Kapoussi with the Porta Sidhera (Σιδηρᾶ Πύλη, meaning “Iron Gate”), mentioned in Byzantine texts as being near the Convent of the Petrion. This connection seems reasonable given its proximity to known landmarks and the historical importance of the convent.
The Extent and Features of the Petrion
The Petrion district was not limited to the fortified enclosure itself. It also extended to adjacent areas outside the inner wall. This is evident from historical references that mention towers in the Petrion, even though the stretch of wall between Porta Phani and Porta Petri had no towers at all. Therefore, the name “Petrion” likely referred to a broader area that included both the Castron and its neighbouring territories.
Churches and Monasteries in the Petrion
The Petrion quarter was rich in religious institutions. Among its churches were St. Stephen of the Romans, St. Juliana, St. Elias, and St. Euphemia, the last two being especially important.
The Church of St. Euphemia was one of the oldest Christian foundations in the city, said to have been built before Constantinople even existed. Tradition attributes its foundation to Castinus, Bishop of Byzantium between 230 and 237 CE. It was later restored by Emperor Basil I, whose daughters entered the convent attached to the church.
The Convent of the Petrion, associated with St. Euphemia, became an important place in Byzantine society. It was often used to confine noble women who had fallen out of imperial favour. Among those imprisoned there were Zoe, the widow of Emperor Leo the Wise, who conspired against Romanus Lecapenus; Theodora, who was confined by her own sister, the Empress Zoe; and Delassaina, the mother of the Comneni family, along with her daughters and daughters-in-law, who were placed there by Nicephorus Botaniates.
The Petrion in Warfare
The Petrion and nearby Phanar areas were strategically important during naval assaults on the city’s harbour defences. Their position along the Golden Horn made them prominent targets whenever foreign fleets attempted to attack or breach the Harbour Walls. Because of their proximity to both imperial palaces and major monasteries, these gates represented not only military strongholds but also symbols of Byzantine prestige and resilience.
The section of wall between Porta Phani and Petri Kapoussi thus combined strong fortifications, religious heritage, and historical significance. The Castron of the Petrion protected a key district closely associated with the Byzantine aristocracy, imperial families, and the church. Today, the memory of the Petrion survives mainly in the enduring name Petri Kapoussi, a faint echo of one of Constantinople’s most storied quarters.