urban center vs Sardis

urban center and Sardis both are nouns.

Word	Noun	Adjective	Verb	Adverb
urban center	Yes	No	No	No
Sardis	Yes	No	No	No

urban center (noun)	Sardis (noun)
a large and densely populated urban area; may include several independent administrative districts	an ancient Greek city located in the western part of what is now modern Turkey; as the capital of Lydia it was the cultural center of Asia Minor; destroyed by Tamerlane in 1402