metropolis vs Rostov na Donu

metropolis and Rostov na Donu both are nouns.

Word	Noun	Adjective	Verb	Adverb
metropolis	Yes	No	No	No
Rostov na Donu	Yes	No	No	No

metropolis (noun)	Rostov na Donu (noun)
people living in a large densely populated municipality	a seaport on the Don River near the Sea of Azov in the European part of Russia
a large and densely populated urban area; may include several independent administrative districts