Vahnstad
Emperor
I'm back and forth. The thing isn't a caravansary, because there aren't interior stalls. It's also very sea-oriented. It is partially fortified, but not enough to make it some kind of citadel or castle. So to me, it's likely a feitoria, or something that fulfills the same role.
BUT...
There doesn't seem to be many world famous fortified seaside warehouses.
So maybe a UI? But it doesn't match Portuguese or Dutch architecture. Maybe some Islamospheric sea-going trade civ?
Unique Improvement of Kilwa / Swahili?