They both belong, as Forchheimer and Strygowski have incontestably shown, to the age of Justinian. The capitals of the columns of the Bin Bir Derek are much plainer than those of the Yeri Batan Serai. Strygowski thinks that there the new impost capital was first used.
"It is of the widest significance for the history of Byzantine art that here throughout the new 'impost capital' is employed in its plainest constructive form. It seems not improbable that the daring builder of the cistern was the first to make use of this form of capital, which completely broke with classical tradition, and is in such perfect accord with the exigencies of arch-architecture." But the analysis of the varieties of capital made by Lethaby and Swainson shows that the impost capital had probably been in use some years before the building of the Bin Bir Derek.
The descent through a trap door and some worn steps from the stableyard of a Turkish house into the Yeri Batan Serai, lighted by a torch extemporised of sacking steeped in naptha, and wrapped round a pole, is an exciting experience. As you look out into the darkness you do not wonder that weird stories have grown up around its recesses, or that Gyllius who discovered it has a strange experience to record.[70]
"Through the Carelesness and Contempt of everything that is curious in the Inhabitants, it was never discover'd, but by me, who was a Stranger among them, after a long and diligent Search after it. The whole Ground was built upon, which made it less suspected there was a Cistern there. The People had not the least Suspicion of it, although they daily drew their Water out of the Wells which were sunk into it. I went by Chance into a House, where there was a Descent into it, and went aboard a little Skiff. The Master of the House, after having lighted some Torches, rowing me here and there a-cross, through the Pillars, which lay very deep in Water, I made a Discovery of it. He was very intent upon catching his Fish, with which the Cistern abounds, and spear'd some of them by the Light of the Torches. There is also a small Light which descends from the Mouth of the Well, and reflects upon the Water, where the Fish usually come for Air. This Cistern is three hundred and thirty six Foot long, a hundred and eighty two Foot broad, and two hundred and twenty four Roman Paces in Compass. The Roof, and Arches, and Sides, are all Brickwork, and cover'd with Terrass, which is not the least impair'd by Time. The Roof is supported with three hundred and thirty six Marble Pillars. The Space of Intercolumniation is twelve Foot. Each Pillar is above forty Foot nine Inches high. They stand lengthways in twelve Ranges, broadways in twenty-eight. The Capitals of them are partly finish'd after the Corinthian Model, and part of them not finish'd. Over the Abacus of every Pillar is placed a large Stone, which seems to be another Abacus, and supports four Arches. There are abundance of Wells which fall into the Cistern. I have seen, when it was filling in the Winter-time, a large Stream of Water falling from a great Pipe with a mighty Noise, till the Pillars, up to the Middle of the Capitals, have been cover'd with Water. This Cistern stands Westward of the Church of St. Sophia, at the Distance of eighty Roman Paces from it."