Around the Blue Mosque - Strolling Through Istanbul: The Classic Guide to the City - page 124

In SS. Sergius and Bacchus, as in almost all of the surviving
Byzantine churches of the city, we must simply use our imagination in
order to recapture the extraordinary beauty of its original condition.
The walls, like those of Haghia Sophia, were revetted with veined and
variegated marbles; the vaults and domes glittered with mosaics. “By
the sheen of its marbles it was more resplendent than the sun,” says
Procopius, “and everywhere it was filled profusely with gold.”
SS. Sergius and Bacchus continued to serve as a church for nearly
1,000 years after its founding, but then in the first decade of the
sixteenth century it was converted into a mosque. Its patron at that
time was Hüseyin Ağa, who was Kapıağası, or Chief of the White
Eunuchs, in the reign of Beyazit II. Hüseyin Ağa's tomb can still be
seen in the garden to the north of the church. The building is now
called Küçük Aya Sofya Camii, the mosque of Little Haghia Sophia,
because of its supposed resemblance to the Great Church.
Just to the north of the church, on Küçük Aya Sofya Caddesi, we
find an ancient bath, Çardaklı Hamam. An inscription shows that
it was built in 1503 by a Kapıağası under Beyazit II; its date and its
proximity to Küçük Aya Sofya Camii suggest that the founder may
have been Hüseyin Ağa. The hamam is ruinous and unusable but
must have been quite grand.
Returning to the church we pass through the courtyard once again
and leave by the gate through which we first entered. Retracing our
steps for a short distance, we then turn left to follow a winding lane
which passes under the railroad line and eventually leads us out to the
Marmara shore. Here we turn left and follow the ancient Byzantine
sea walls along the Marmara.
ALONG THE SEA WALLS
The sea walls in the section along which we are walking were
originally constructed by Constantine the Great, ending where his
land walls met the sea at Samatya. When the Theodosian walls were
built in the following century, the Marmara sea walls were extended
to meet them. During the ninth century, the Marmara walls were
almost completely rebuilt by the Emperor Theophilus, who sought
to strengthen the city's maritime defences against the Saracens. The