Brewer's: City of Palaces
(The). Agrippa, in the reign of Augustus, converted Rome from “a city of brick huts to one of marble palaces.” (Cf. Suetonius.) Calcutta is called the “City of Palaces.” Modern Paris well deserves the compliment of being so called.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894