Constantinople was more advanced because it thrived even when the western part of the Roman Empire fell. It was quite possibly the most advanced part of Europe at that time, while Western Europe was in complete disarray.
There have been many sieges of Constantinople. You will have to be more specific.
One Opinion:My own view is that depending on the time in the Middle Ages and what is meant by advanced, the most advanced cities in Europe were probably Constantinople, Cordoba, Paris, London, and Lübeck. Other people will have other opinions.
They were more advanced because they had more medical people and were much more advanced in technology.
Advanced math
The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.The Romans ad a more advanced civilization than the barbarians.
Squid are considered more advanced than clams.
Constantinople
additional= more than required advanced= more harder than regular
South Korea is economically more advanced.
japan is the most advanced
as (so) advanced as,(comparative of equality) / more advanced than,(comparative of superiority) / the most advanced of (all).(Superlative)
A Pentium 4 processor is more advanced because it is faster and able to do much more complex calculations. It will, however, be superseded by a more advanced processor eventually.