Modern Halawiyya Mosque and Madrasa complex that dates to the 5th century was originally Aleppo's great Byzantine cathedral. According the tradition built by Saint Helena (246-330) mother of Constantine the Great (272-337).
See:
- https://web.archive.org/web/20120928191428/http://www.sonic.net/~tallen/palmtree/ayyarch/ch2.htm#alep.mhal
- http://archnet.org/library/sites/one-site.jsp?site_id=2693
- Howard Crosby Butler: Early Churches in Syria. Fourth to Seventh Centuries. Princeton University Press, Princeton 1929, p. 170-171