This article accompanies the fable
Arguably the most brilliant poem about aging ever written, Yeats' Sailing to Byzantium (written 1926-27) is about sailing off into eternity. I deliberately chose an image not from Byzantium itself, because Byzantium is a state of mind. To attempt to identify its meaning in Istanbul misses the point. Yeats never got there - Italy was as far East as he got. Byzantium can be anywhere really, a timeless world inhabited nonetheless by real human beings passing through it. But it seems to be on the coast.
The image at top is of the Cliff House, that graced the San Francisco coastline at Point Lobos, just SW of today's Golden Gate from 1896 till 1907, when it was burnt to the ground. It was highly romantic then and it still is. The ocean sweeps around the heads into San Francisco Bay like the Bosporus and Golden Horn at Istanbul. After the original Cliff House burnt down, another rose in its place (you can see the current version below). Nearby are the ruins of the Sutro Baths, which also opened in 1896 and which burnt down in 1966. The image struck me as Yeatsian. But I think this is what he was thinking of:
This poem and its successor, Byzantium, are about what Yeats once referred to as "the search for the spiritual life." For me, it's exploring aging and finding pleasure in the wisdom (sophia) that comes with it - or should. It also fits into a Western (specifically Irish) Orientalism.
The prophetic golden bird alluded to in the last stanza recalls Hans Christian Andersen's The Nightingale and others are reminded of Jerusalem and the Sacred City of the Apocalypse of St. John.
For related links see here (Yeats) and here and here (Orientalism). Below is Cliff House today - its fifth incarnation - restaurants...