Which city was the largest and wealthiest city in Europe from the mid-5th century to the early 13th century?

I guess I don't know what 'sacked' means. Ransacked? Books stolen? destroyed or? Then you say it WAS the holder of those holy relics; but do not say if they're still there or if they still exist.

Flower Lady, Constantinople, the jewel of Christianity, was sieged, destroyed, and all inhabitants slaughtered by Islamic invasion. Interestingly, nobody talks about it much.

The Queen of Cities, Istanbul (was Constantinople)

By the help of the picture, I guessed the right answer!