This is the story of a complete waste of time. Paspates made a lithograph of a pretty octagonal mescit in the Laleli area in the 1870s. Van Millingen argued over the purpose of the building in Byzantine times and concluded that it was probably a funeral chapel. Whatever it was, the municipality decided that the demands of city planning meant that it had to go and they would build the shopping street of Harikzedelar Sokak over the remains.
The TAY website places the location of the building at around A on the map but also points out some Byzantine remains in the basement of nearby Adem İşhane (B). Eminönü Belediyesi’s official map of mosque locations places it at C. There was a car park here, often a useful way of keeping a space open so foundations can be seen, but there were none.
Adem İşhane is no longer there – it has been split into individual shops. The people in the basement shop had heard of the remains but except for the entrance, their shop was bounded on all sides by 21st century concrete. They suggested trying to approach from the street behind. Here, there was an enormous building site. The workers raised no objection to me going into the basement, four floors of sealed concrete. Maybe if I had come three months earlier, I would have witnessed the edifying spectacle of a man with a pneumatic drill blasting thousand-year-old masonry into dust.
I spent more time looking for nothing than I would have exploring an intact church. Still, there are some fragmentary remains in the Archaeological Museum. These bits in the grounds of nearby Laleli Camii might be from the Balaban Ağa Mescidisi. Or they might not.