What was the richest city in Europe 12th century and why?

The richest city in Europe in the 12th century was Constantinople, today Istanbul, Turkey. It was the capital of the Byzantine Empire and was one of the largest and most powerful cities in Europe. Constantinople was a major center of trade and culture, and its wealth was due to its strategic location on the Bosporus Strait, which connects the Black Sea to the Mediterranean Sea. This made it a hub for trade between Europe and Asia, and it was home to many rich and powerful merchants. Additionally, Constantinople was the center of the Byzantine Empire, which was one of the wealthiest and most powerful empires in Europe at the time.