The Theodosian land walls have their walk. The Marmara sea walls — Byzantine, fragmentary, less famous — have one too, and almost no tourists know it. They enclosed the southern shore of the peninsula from the same period as the land defences, and what survives is patchy but visible, particularly along Ahırkapı.
Three kilometres, mostly flat, finishing with a short climb up to Hagia Sophia from the south side — the way tourists never come. Cankurtaran Marmaray drops you a few minutes from the sea-wall stretch. Ahırkapı Feneri is the working lighthouse at the seaward corner; Topkapı's foundation walls rise above it. Kennedy Caddesi runs west along the water — concrete now, but the perimeter is the perimeter.
The climb at the end is the trick. Coming up from Cankurtaran toward Hagia Sophia, the south facade reveals itself in a way the Sultanahmet plaza side never does. Mass first, decoration second. The Sultanahmet tram is two minutes from the dome, and the T1 west takes you out to Yedikule if you want to do the land walls the same afternoon.
