Athens vs national capital

Athens and national capital both are nouns.

Word	Noun	Adjective	Verb	Adverb
Athens	Yes	No	No	No
national capital	Yes	No	No	No

Athens (noun)	national capital (noun)
the capital and largest city of Greece; named after Athena (its patron goddess)	the capital city of a nation
a university town in northeast Georgia
a town in southeast Ohio