"A city known for 7 Mountains sounds like Rome. Rio De Janeiro has 7 hills, but never ruled the world. Rome is known as the 'CITY OF 7 HILLS' not 7 mountains though, so let's not use that reference as more than a curiosity."
Constantinople, now Istanbul, was built on seven hills and was the seat of the Eastern Roman Empire.
Re: Seven hills vs. seven mountains
How high do you want to go?
http://7summits.com/