The Christian Church was the single most powerful social organization in Europe from the Middle Ages to the end of the Victorian era.
church?
The cathedrals
clergy
romans
churches
they took steroids
Roman Catholic
Khloe Kardashian
the united kingdom and states of great britain
because muslims rock!
Charlemagne was without doubt the most powerful man in western Europe in the Early Middle Ages. He ruled a country that included most or all of current France, Germany, Switzerland, the Netherlands, and Belgium, along with major parts of Italy and Austria.
Most cities were parts of countries and did not have real independent power. Venice was one that was independent, and was probably the most powerful of those. There is a link below.