Byzantine Church in Athens: Great Virgin
In the early 5th C the reading room (anagnosterion) of Hadrians Library was arranged as a Chrisitian church, which was called the Great Virgin on account of its large dimensions.
The church had a central square open space in which four conches were opened, hence it is alternatively known as the Tetraconch.
Remnants of the monument can still be seen today in situ: the semi-circular sanctuary apse, three columns and the base of the southern collonade.
The floor was paved with mosaics. The building was destroyed by fire in the late 5th C and was replaced by a new church of the Middle Byzantine period.