I often complain about the texts in English produced by Turkish authorities. Here is an example (from a gov.tr site): " THE YENİŞEHİR DOOR: The most interesting parts of the magnificent Iznik walls were cut with stones in the first century AD. The Yenişehir Gate consists of three sections. The door leading to the first entrance of the city is connected to the front side, the western part is connected to the fortification, and the eastern part is connected to a small fortification. The inner door is reached by passing a square yard. It is documented that the chisel is covered with antique pieces, but there are very few permits daily." If you understand what the last sentence means without looking at the Turkish text I think you’re a genius. And it would help if the text stopped calling gate a “door”.
I found in a book I have that the oldest part of this gate was built in 269 by Claudius Gothicus.

View from ouside the wall.