Eternal City vs Seven Hills of Rome

Eternal City and Seven Hills of Rome both are nouns.

Word	Noun	Adjective	Verb	Adverb
Eternal City	Yes	No	No	No
Seven Hills of Rome	Yes	No	No	No

Eternal City (noun)	Seven Hills of Rome (noun)
capital and largest city of Italy; on the Tiber; seat of the Roman Catholic Church; formerly the capital of the Roman Republic and the Roman Empire	the hills on which the ancient city of Rome was built