At the time the Templars were formed, THE city – the most important metropolis in Europe – was still Constantinople. It may no longer have dominated the Mediterranean as it had done in the late Roman period and under Justinian and his immediate successors, but it remained a wealthy and prospering entrepot.
The armies of Islam – against whom the crusaders and Templars would fight throughout the 12th and 13th centuries might have taken north Africa and the Levant from the Christian emperor in Constantinople – but it still exerted a huge political, cultural and occasionally military pull on the region. It was, after all, an appeal from the emperor that led the pope to call for the First Crusade.
Constantinople survived because it sat behind huge, thick walls built in the 5th century AD to withstand attacks from Huns and other barbarians. It saw off the Arabs, Bulgars, Avars and Turks in succession. By the year 1200, the population believed their mighty city could see off any invader and yet, four years later, fellow Christians would attack and devastate the city, breaching its walls, in the Fourth Crusade.
There have been several attempts to recapture the glory of Constantinople through simulation and I share a couple here.