The Golden Gate was first a Roman triumphal arch erected in about 390 by Theodosius I the Great. The walls had not been built at the time, so the gate stood by itself on a road (Via Egnatia) about a mile outside the walls of Constantine. The opening was bricked up later in Byzantine times.

This is one of a number of shots I took from one of the pylons flanking the gate. I am not certain this is actually part of the Golden Gate proper. It looks plenty ancient.