[1]This wall is still standing among almost impenetrable vegetation.
The halting of train services from Sirkeci for work on the Marmaray means that in 2014 nobody really cares if you wander about on the railway track and hack about in the jungle below the walls of Topkapı Sarayı. If you break through the sea walls near the statue of Turgut Reis and head across the tracks, there is an exciting-looking building for those of us who enjoy scrabbling about in subterranean muck.
As of March 2016, the possibility of ad hoc exploration of this site has been reduced severely. The military has installed a businesslike razor-wire fence with watchtowers and alert guards on the western side of the railway line. No more little expeditions to this part of Istanbul for a while.
[2]Entrance in south wall
The vault is fairly intact and there is some above-ground brickwork. This may be the remains of the Church of St George of the Manganes (41.012171,28.986778).
[3]Vault and makeshift housing
[4]High vaultage
The Palace of the Manganes is a little further west (41.010022,28.987159) and provides extensive remains for tunnelling and feeling intrepid. There are a few rather nice pieces of Byzantine stonework but the original alignment and relative positions of them have been lost through earth movements over the centuries.
[5]Vaults of the Palace of the Manganes
[6]Sculpted bits of the Palace of the Manganes in situ underground
[7]Column capitals from Mangana Church, Archaeological Museum of Istanbul.
[8]