Biggest Cities of the Byzantine Empire in 1453 - Under Constantine XI

This would be mere months before the end of the Eastern Roman Empire, although the Roman vassal state of the Duchy of Athens would only fall by 1458 and the appanage territory of the Despotate of the Morea would persist until 1460, with the final resistance ending as late as July 1461 with its final conquest by the Ottomans.

Rump states of the Roman state would also remain for a few more years, e.g. the Empire of Trebizond (ended 1461) and the Principality of Theodoro (ended 1475), both also falling to the Ottoman Empire.