The Mosque–Cathedral of Córdoba, also known as the Great Mosque of Córdoba, whose ecclesiastical name is the Cathedral of Our Lady of the Assumption,is the Catholic cathedral of the Diocese of Córdoba dedicated to the Assumption of the Virgin Mary and located in the Spanish region of Andalusia. The structure is regarded as one of the most accomplished monuments of Moorish architecture.

According to a traditional account, a small Visigoth church, the Catholic Basilica of Saint Vincent of Lérins, originally stood on the site. In 784 Abd al-Rahman I ordered construction of the Great Mosque, which was considerably expanded by later Muslim rulers. Córdoba returned to Christian rule in 1236 during the Reconquista, and the building was converted to a Roman Catholic church, culminating in the insertion of a Renaissance cathedral nave in the 16th century.

Since the early 2000s, Spanish Muslims have lobbied the Roman Catholic Church to allow them to pray in the cathedral. This Muslim campaign has been rejected on multiple occasions, both by the church authorities in Spain and by the Vatican.

It is commonly believed that the site of the Mosque-Cathedral was originally a Christian church dedicated to Saint Vincent the Third, which was divided and shared by Muslims and Christians after the Islamic conquest of the Visigothic kingdom. This sharing arrangement of the site lasted until 784, when the Christian half was purchased by the Emir Abd al-Rahman I, who then proceeded to demolish the original structure and build the grand mosque of Córdoba on its ground. This narrative, which goes back to the tenth-century historian al-Razi, echoed similar narratives of the Islamic conquest of Syria, in particular the story of building the Great Mosque of Damascus.

For medieval Muslim historians, these parallels served to highlight a dynastic Umayyad conquest of Spain and appropriation of the Visigothic Córdoba. The historicity of this narrative has been challenged, as archaeological evidence is scant, and the narrative is not corroborated by contemporary accounts of the events following Abd al-Rahman I’s initial arrival in al-Andalus.

Another tenth-century source mentions a church that stood at the site of the mosque without giving further details. However, it is almost certain that the building which housed the original mosque was destroyed to build the first version of the Great Mosque. An archaeological exhibit in the Mosque–Cathedral of Cordoba displays fragments of a Visigothic building, emphasizing an originally Christian nature of the complex.

According to Susana Calvo Capilla, a specialist on the history of the Mosque–Cathedral, although remains of multiple church-like buildings have been located on the territory of the Mosque-Cathedral complex, no clear archaeological evidence has been found of where either the church of St. Vincent or the first mosque were located on the site, and the latter may have been a newly constructed building. The evidence suggests that it may have been the grounds of an episcopal complex rather than a particular church which were initially divided between Muslims and Christians.

According to a traditional account, when the exiled Umayyad prince Abd al-Rahman I escaped to Iberia and defeated the governor of Al-Andalus, Yusuf al-Fihri, he found the Cordovese divided into various sects, including the Gnostics, Priscillianists, Donatists, and Luciferians. His ambition was to erect a temple which would rival in magnificence those of Baghdad, Jerusalem, and Damascus, and approach in sanctity the fame of Mecca. Above a Christian church dedicated to Saint Vincent, Abd al-Rahman decided to raise his great mosque. He offered to buy the church and the plot. The negotiations for the sale were placed in the hands of the Sultan’s favourite secretary, Umeya ibn Yezid. Under the terms of the transfer, the Cordovese were permitted to reconstruct the church formerly dedicated to Saints Faustus, Januarius, and Marcellus, three Christian martyrs whom they deeply revered.

Abd al-Rahman allowed the Christians to rebuild their ruined churches and purchased the Christian half of the church of St Vincent, as agreed upon in the sale terms. The Emirate was rich. Apart from the treasure wrested from the Goths during the recent wars, he also extracted a tithe upon the produce of the land and on manufactures. All able Muslims in Andalusia were asked to pay the zakat. A mandatory tax known as jizya was also laid upon only one able Christian and Jew per household in Andalusia as a precondition for services & protection provided by the government of Andalusia, unless they participated in the protection services themselves.

The Jizya was lesser than the Zakat and both were one of the main sources of income for the Muslim rulers in lands occupied by Islamic tribes but populated still by Christians, to provide all needed services for all people living in the land, especially the poor. Beyond this, the Moorish kings were greatly enriched by the acquisition of the valuable mines of Iberia, the quarries of marble, and other sources of wealth. From these revenues Abd al-Rahman and his successors, Hisham, Abd-al Rahman II, the greatest of the dynasty and the third of the line, and lastly the extravagant Almanzor, lavished large sums upon the designing, construction, and costly adornment of the Mosque. Abd al-Rahman I and his descendants reworked the building over the next two centuries to fashion it as a mosque, starting in 784. Additionally, Abd al-Rahman I used the mosque (originally called Aljama Mosque) as an adjunct to his palace and named it in honour of his wife. Traditionally, the mihrab (or apse) of a mosque faces in the direction of Mecca; by facing the mihrab, worshipers pray towards Mecca. Mecca is east-southeast of the mosque, but the mihrab of this mosque unusually points south.

The work of building the resplendent Mezquita employed thousands of artisans and labourers, and such a vast undertaking led to the development of all the resources of the district. Hard stone and beautifully veined marble were quarried from the Sierra Morena and the surrounding regions of the city. Metals of various kinds were dug up from the soil, and factories sprang up in Córdoba amid the stir and bustle of an awakened industrial energy. A famous Syrian architect made the plans for the Mosque. Leaving his own house on the edge of Córdoba, the Emir came to reside in the city, so that he might personally superintend the operations and offer proposals for the improvement of the designs. Abd al-Rahman moved about among the workers, directing them for several hours of every day.

The mosque underwent numerous subsequent changes: Abd al-Rahman II ordered a new minaret, while in 961 Al-Hakam II enlarged the building and enriched the Mihrab. The last of such reforms was carried out by Almanzor in 987. It was connected to the Caliph’s palace by a raised walkway, mosques within the palaces being the tradition for previous Islamic rulers – as well as Christian Kings who built their palaces adjacent to churches. The Mezquita reached its current dimensions in 987 with the completion of the outer naves and courtyard.

In planning the mosque, the architects incorporated a number of Roman columns with choice capitals. Some of the columns were already in the Gothic structure; others were sent from various regions of Iberia as presents from the governors of provinces. Ivory, jasper, porphyry, gold, silver, copper, and brass were used in the decorations. Marvellous mosaics and azulejos were designed. Panels of scented woods were fastened with nails of pure gold, and the red marble columns were said to be the work of God. The primitive part of the building, erected under the direction of Abd al-Rahman I., was that which borders the Court of Oranges. Later, the immense temple embodied all the styles of Morisco architecture into one composition.

The Great Mosque of Córdoba held a place of importance amongst the Islamic community of al-Andalus for three centuries. In Córdoba, the capital, the Mosque was seen as the heart and central focus of the city. Muhammad Iqbal described its hypostyle hall as having “countless pillars like rows of palm trees in the oases of Syria”. To the people of al-Andalus “the beauty of the mosque was so dazzling that it defied any description.”

The main hall of the mosque was used for a variety of purposes. It served as a central Prayer hall for personal devotion, the five daily Muslim prayers and the special Friday prayers. It also would have served as a hall for teaching and for Sharia law cases during the rule of Abd al-Rahman and his successors.

The Great Mosque of Córdoba exhibited features and an architectural appearance similar to the Great Mosque of Damascus, which may have been used as a model.