The Fifth and Sixth Hills - Strolling Through Istanbul: The Classic Guide to the City - page 265

the middle of a large open area, one can walk around it and look at
it from all sides, unlike most of the other Byzantine churches in the
city. The south and east façades are especially charming with their
characteristic ornamental brickwork, the marble cornices beautifully
and curiously inscribed, the three little apses of the side chapel, and
the multiplicity of domes on high and undulating drums.
The building consists of a central church with a narthex; a small
chapel on the south; and a curious “perambulatory” forming a side
aisle on the north, an outer narthex on the west, and two bays of
an aisle on the south in front of the side chapel. Each of these three
sections was radically altered when it was converted into a mosque
in 1591. The work of the Byzantine Institute has at last cleared up
many of the puzzles arising from the various periods of construction
and transformation. It now appears that the main church was built in
the twelfth century by an otherwise unknown John Comnenus and
his wife Anna Doukaina. In form, the church was on the ambulatory
type, a triple arcade on the north, west and south dividing the
central domed area from the ambulatory; at the east end were the
usual three apses, at the west a single narthex. At the beginning of
the fourteenth century a side chapel was added at the south-east as a
mortuary for Michael Glabas and his family; this was a tiny example
of the four-column type. In the second half of the fourteenth century,
the north, west and part of the south sides were surrounded by the
“perambulatory”, which ran into and partly obliterated the west
façade of the side chapel. When the building was converted into a
mosque, the chief concern seems to have been to increase the available
interior space.
Most of the interior walls were demolished, including the arches of
the ambulatory; the three apses were replaced by the present domed
triangular projection; and the side chapel was thrown into the mosque
by removing the wall and suppressing the two northern columns. All
this can scarcely be regarded as an improvement. Indeed, the main
area of the church has become a dark, planless cavern of shapeless
hulks of masonry joined by low crooked arches. This section has now
been divided of from the side chapel and is again being used as a
mosque.