Before the Ottoman conquest of 1453, Constantinople was a predominantly Christian city, serving as the heart of the Byzantine Empire. Yet historical records reveal moments of Muslim presence within its walls-diplomatic, commercial, and even religious. A small number of Muslims lived, worshipped, and even fought alongside Christians at critical moments in the city’s history. From early prayer spaces built for Arab generals to the destruction of a mosque during the Fourth Crusade, these episodes reveal a more layered and interconnected past than often assumed.
Early Evidence of Muslim Presence and Worship in Constantinople
The earliest known evidence of a permanent Muslim place of prayer (masjid) in Constantinople appears in a remarkable letter written by Nicholas I Mystikos (852 – 15 May 925, see footnote 1), Patriarch of Constantinople, to the Abbasid Caliph al-Muqtadir in July 921 AD. This letter addresses the caliph’s concern over a rumor-one which Nicholas strongly denounces as a fabrication of the Devil-claiming that imperial authorities had destroyed the Muslim oratory (εὐκτήριον) in Constantinople and that local Muslims were being forced to convert to Christianity under duress.
This document is significant not only for what it tells us about Byzantine-Islamic diplomatic communication but also for what it implies: that by the early 10th century, Muslims had access to a recognized place of worship within the Byzantine capital. The oratory (sometimes translated from Greek as Maison de prière) was likely used by visiting Muslim merchants, diplomats, and possibly even long-term residents.
The Maslama Mosque and Imperial Recognition
Further confirmation of the existence of a Muslim prayer space in Constantinople comes from the Byzantine emperor Constantine VII Porphyrogenitus (see footnote 2) in his treatise De Administrando Imperio, written around 950 AD. In this work, Constantine recounts the events of the Umayyad siege of Constantinople (717-718 AD), led by the capable general Maslama ibn ʿAbd al-Malik. While the siege ultimately failed, relations between the Byzantines and Maslama’s forces were complex, involving negotiations and even temporary accommodations.
According to Constantine VII, it was at Maslama’s request that a structure referred to in Greek as a μαγίσδιον (magisdion)-a Hellenized form of the Arabic masjid (mosque)-was built within the imperial precinct known as the Praetorium. While it’s unclear whether this was a temporary or permanent structure, its construction indicates a moment of diplomatic flexibility and religious tolerance, at least in the context of military engagement.
The precise location of this early Muslim prayer site remains unknown. However, the 10th-century Arab geographer al-Muqaddasī mentions a Muslim presence in Constantinople and may offer clues as to its whereabouts. His writings suggest that Muslims not only visited but perhaps also lived within or near the city’s commercial districts, likely for reasons of trade and diplomacy.
That a masjid could be built in or near the imperial quarter implies a level of formality and recognition rarely associated with pre-Ottoman Muslim communities in Christian-majority cities. It may have served a diplomatic function -similar to embassies or consulates in later eras- providing a spiritual space for foreign dignitaries, emissaries, or soldiers under truce.
A Prison, Not a Mosque? Alternate Interpretations
Some historians argue that the structure in question may never have been a dedicated mosque or even built at Maslama’s request. Instead, they suggest it originated as a place of detention for high-ranking Muslim prisoners, who were granted limited privacy and religious freedom during captivity.
This interpretation finds support in the writings of the 10th-century Muslim geographer al-Muqaddasī, who describes the Dār al-Balāṭ as a location associated with imperial imprisonment in Constantinople. Another Byzantine source corroborates this placement, locating the structure within or near the imperial prison complex.
According to this view, the space used by imprisoned Muslim elites may have eventually taken on a quasi-religious role, especially if communal prayers-like the Friday congregational prayer-were permitted there. Over time, its function as a temporary place of worship may have been remembered and romanticized in local lore, and the association with Maslama ibn ʿAbd al-Malik possibly emerged later as a product of evolving popular tradition rather than historical fact.
The Fourth Crusade and Muslim-Christian Solidarity
Fast forward to the early 13th century: during the Fourth Crusade (1203-1204), when Latin Crusaders and Venetian forces laid siege to Constantinople, historical sources indicate that both Orthodox Christians and Muslims stood together in defense of the Byzantine capital. This moment of interfaith solidarity is one of the lesser-known but fascinating aspects of the siege.
Byzantine Greek historian and politician Niketas Choniates (c. 1155 – 1217, see footnote 6) recounts the events as follows:
By that time, the Mitaton Mosque stood near the shore of Constantinople. It had been constructed earlier by Emperor Isaac II Angelos as a diplomatic gesture toward the Ayyubid sultan Saladin – another example of Constantinople’s periodic openness to formal Muslim presence, particularly for trade and political alliance.
Tragically, the Latin Crusaders targeted the Mitaton Mosque early in their campaign. As Niketas Choniates recounts, the Latins torched the mosque, igniting a blaze that spread throughout nearby districts, contributing significantly to the widespread destruction that accompanied the infamous sack of the city in 1204. The fire -symbolically and literally- marked the end of a relatively tolerant chapter in Constantinople’s interaction with the Muslim world.
Footnotes
- Nicholas I Mystikos (c. 852-925) was the Patriarch of Constantinople and a key political and religious figure during the early 10th century. Appointed patriarch in 901, he clashed with Emperor Leo VI over the emperor’s fourth marriage and was briefly deposed. Later reinstated, he played a crucial diplomatic role in Byzantine-Abbasid relations. His 921 letter to Caliph al-Muqtadir is one of the earliest sources mentioning a Muslim place of worship in Constantinople, offering rare insight into the interfaith dynamics of the period.
- Constantine VII Porphyrogenitus (905–959 AD) was a Byzantine emperor of the Macedonian dynasty, renowned as a scholar and writer. Born “porphyrogenitus” (meaning “born in the purple”), he was the legitimate son of Emperor Leo VI. Though he reigned officially from 913 to 959, he held limited power for much of his early reign due to regents and military strongmen. Constantine is best known for his scholarly works, especially De Administrando Imperio (On imperial administration) and De Ceremoniis (in non-specialist English sources, it tends to be called the Book of Ceremonies of Constantine VII Porphyrogennetos), which offer valuable insight into Byzantine politics, diplomacy, and court rituals. His reign is considered a cultural high point of the 10th-century Byzantine Renaissance.
- Muʿāwiya ibn Abī Sufyān: Muʿāwiya I (c. 602-680 CE) was the founder and first caliph of the Umayyad Caliphate, ruling from 661 until his death in 680. A member of the Quraysh tribe and the son of Abū Sufyān, a prominent opponent-turned-supporter of Muhammad, Muʿāwiya initially served as governor of Syria under the Rashidun caliphs. After the first Muslim civil war (the First Fitna), he established dynastic rule, moving the caliphate’s political center from Medina to Damascus. In Byzantine sources, he is often mentioned in the context of early Muslim military pressure on the empire, including naval raids and attempts to besiege Constantinople.
- Maslama ibn ʿAbd al-Malik: Maslama (c. 685-738 CE) was a prominent Umayyad prince and general, the son of Caliph ʿAbd al-Malik and a half-brother of several later caliphs. He is best known for leading the massive siege of Constantinople from 717 to 718 CE during the reign of Emperor Leo III. Though the siege ultimately failed due to harsh winter conditions, a Byzantine-Naval alliance, and the use of Greek fire, Maslama remained a respected figure in Islamic military history. His involvement with the construction of a magisdion near the Imperial Palace suggests a temporary Islamic religious presence in or near Constantinople during his campaign.
- Magisdion (μαγίσδιον): The term magisdion (Greek: μαγίσδιον) appears to refer to a temporary or semi-permanent place of worship, likely a prayer space or oratory (εὐκτήριον) established for Muslim use. In this context, it seems to refer to a structure built at the request of Maslama during the siege of Constantinople in the early 8th century. It may have served as a makeshift mosque or prayer tent for the Muslim forces near or within the Imperial Praetorium (a central administrative or ceremonial complex). The term is rare and appears in Byzantine sources to describe foreign or unconventional religious structures.
- Niketas Choniates (c. 1155–1217) was a Byzantine historian, high-ranking official, and eyewitness to the fall of Constantinople during the Fourth Crusade in 1204. Born in Asia Minor, he held various imperial posts and later fled to Nicaea after the Latin conquest. His major work, Historia, offers a vivid and critical account of the Byzantine Empire’s decline from 1118 to 1207. Rich in political insight and rhetorical style, his writings are a key source for understanding the empire’s final centuries.
Sources
- Is there any evidence of Muslims living in Constantinople before the Ottoman conquest of the city? Answers by the Historian Federico León and Eleftherios Tserkezis on Quora
- Nicholas Mystikos on Wikipedia
- Mu’awiya I on Wikipedia
- Fourth Crusade on Wikipedia
- Constantine VII on Wikipedia
- Nicholas Mystikos on Wikipedia
- Niketas Choniates on Wikipedia
