cograecia_
p. 190.

[442] The question thus raised presents serious difficulties. That
some building[A] in the neighbourhood of Kefele Mesjedi was known by
the name of Aetius[B] is undoubted. It was a cistern (Du Cange, i. p.
96), and formed one of the landmarks by which the church of S. John in
Petra, situated in this quarter of the city, was distinguished (Du
Cange, iv. p. 152 [Greek: engista tou Aetiou]). But while that is the
case, Gyllius (_De top. C.P._ iv.), who explored this part of the city
in 1550, does not mention any Byzantine church that answers at all to
Gerlach's description of the church of Aetius, unless it be the Chora.
That Gyllius should have overlooked so beautiful a monument of
Byzantine days as the church of Aetius, if different from the Chora,
is certainly very strange. But it is not less strange to find that
Gerlach does not speak of the Chora. Can the difficulty thus presented
be removed by the supposition that Gerlach refers to the Chora under
the name of Aetius? The position he assigns to the church of Aetius in
relation to the church of S. John in Petra and to the palace of
Constantine (Tekfour Serai) favours that view, for he places the
church of Aetius between S. John and the palace, exactly where the
Chora would stand in that series of buildings. Looking towards the
north-west from the windows of a house a little to the east of the
Pammakaristos, Gerlach says 'Ad Occasum, Boream versus, Prodromi
[Greek: mone] est, olim [Greek: petra]; longius inde, Aetii [Greek:
mone]; postea, Palatium Constantini' (_Turcograecia_, p. 190). On the
other hand, Gerlach's description of the church of Aetius differs in
so many particulars from what holds true of the Chora, that it is
difficult, if not impossible, to believe that in that description he
had the latter church in mind. Unless, then, we are prepared to admit
grave mistakes in Gerlach's description, we must either assume an
extraordinary failure on his part and on the part of Gyllius to notice
a most interesting Byzantine monument, directly on the path of both
explorers in this quarter of the city, or regret the disappearance of
an ancient sanctuary that rivalled the Chora in splendour.

[A] It was probably the ruined cistern with twenty-four
columns arranged in four rows of seven pillars each, near
the mosque Kassim Aga, a short distance above Kefele
Mesjedi. Gerlach associates it with the church of Aetius.

[B] _Tageb