We suggest that the circular brick building lying at the north-east angle of the present church belonged to the pre-Justinian church, and formed its baptistery. It is about forty-five feet exterior diameter, and the plan as given by Salzenberg shows great resemblance to other circular structures of the Constantinian age; such as S. Constantia in Rome, the “tomb of Helen” at Rome, and the round tomb buildings which adjoined S. Peter’s as shown in the plan of Ciampini.[40] The entrance doorway of this building was to the _east_. As to its use. In the contemporary account of Justinian’s church, the poet Paulus, describing the north aisle, says, “On the north is a door admitting the people to the founts that purify the stains of mortal life and heal every scar.” He does not mention the present south-west building, nor has he any other reference to a font. We suppose therefore that this isolated building on the north-east escaped the Nika fire, and served as the baptistery of the new church, until the square building, on the side of the church towards the Augusteum, which is spoken of in the _Ceremonies_ as the “Great Baptistery by the Horologium,” was erected for or diverted to this purpose. We very probably have some relics of the earlier buildings in certain capitals which Salzenberg found in the church:[41] the inscribed bricks,[42] and a Byzantine Corinthian capital now lying in the courtyard, may likewise have belonged to it. The fine bronze doors to south porch are evidently earlier than the present church, and so probably are the slabs of which the screen on south side of first floor is partly made up. CHAPTER II JUSTINIAN’S CHURCH _The New Church._--The pre-Justinian church was burnt on the 15th January, 532[43]--the first day of the sedition--and the work of reconstruction was begun on the 23rd of the following month.[44] Theophanes[45] says the period employed in the construction was five years eleven months and ten days; the statements therefore of Codinus and Glycas, that it took seventeen years to build, are completely at variance with this more credible author. The solemn dedication took place, as Marcellinus Comes describes,[46] on 26th December, 537, Indiction 15, in the eleventh year of Justinian’s reign. A description of this dedication ceremony is given by Theophanes.[47] “The procession started from the church of Anastasia, Menas the patriarch sitting in the royal chariot, and the king walking with the people.” In the thirty-second year of Justinian’s reign an earthquake destroyed a great portion of the newly erected church.[48]