existing archeological remains. This theory has in turn been opposed by Fernando Arce-Sainz, another archeologist, who states that none of the numerous archeological investigations in modern times have turned up remains of Christian iconography, a cemetery, or other evidence that would support the existence of a church. Art historian Rose Walker, in an overview of late antique and early medieval art in Spain, has likewise criticized Marfil's view as relying on personal interpretation. The “stratigraphy” of the site is complicated and made more so by its impact on contemporary political debates about cultural identity in Spain. Regardless of what structures may have existed on the site, however, it is almost certain that the building which housed the city's first mosque was destroyed to build Abd ar-Rahman I's Great Mosque and that it had little relation to the latter's form. Construction of the mosque The Great Mosque was built in the context of the new Umayyad Emirate in Al-Andalus which Abd ar-Rahman I founded in 756. Abd ar-Rahman was a fugitive and one of the last remaining members of the Umayyad royal family which had previously ruled the first hereditary caliphate based in Damascus, Syria. This Umayyad Caliphate was overthrown during the Abbasid Revolution in 750 and the ruling family were nearly all killed or executed in the process. Abd ar-Rahman survived by fleeing to North Africa and, after securing political and military support, took control of the Muslim administration in the Iberian Peninsula from its governor, Yusuf ibn Abd al-Rahman al-Fihri. Cordoba was already the capital of the Muslim province and Abd ar-Rahman continued to use it as the capital of his independent emirate. Construction of the mosque began in 785–786 (169 AH) and finished a year later in 786–787 (170 AH). This relatively short period of construction was aided by the reuse of existing Roman and Visigothic materials in the area, especially columns and capitals. Syrian (Umayyad), Visigothic, and Roman influences have been noted in the building's design, but the architect is not known. The craftsmen working on the project probably included local Iberians as well as people of Syrian origin. According to tradition and historical written sources, Abd ar-Rahman involved himself personally and heavily in the project, but the extent of his personal influence in the mosque's design is debated. The original mosque had a roughly square floor plan measuring 74 or 79 square meters per side, equally