In Chapter 2, Part 2 of The History of the Decline and Fall of the Roman Empire, Edward Gibbon writes about what made Rome a “great nation”:

From the foot of the Alps to the extremity of Calabria, all the natives of Italy were born citizens of Rome. Their partial distinctions were obliterated, and they insensibly coalesced into one great nation, united by language, manners, and civil institutions, and equal to the weight of a powerful empire. The republic gloried in her generous policy, and was frequently rewarded by the merit and services of her adopted sons.

Note what her people were united by: “language, manners, and civil institutions.” Note also what they were not united by, the conjecture of which I will leave to the discerning reader.

The Roman position made greatness of a new kind possible. Gibbon goes on to detail some of Rome’s more important non-native sons:

Had she always confined the distinction of Romans to the ancient families within the walls of the city, that immortal name would have been deprived of some of its noblest ornaments. Virgil was a native of Mantua; Horace was inclined to doubt whether he should call himself an Apulian or a Lucanian; it was in Padua that an historian was found worthy to record the majestic series of Roman victories. The patriot family of the Catos emerged from Tusculum; and the little town of Arpinum claimed the double honor of producing Marius and Cicero, the former of whom deserved, after Romulus and Camillus, to be styled the Third Founder of Rome; and the latter, after saving his country from the designs of Catiline, enabled her to contend with Athens for the palm of eloquence.

It is perhaps worth remarking that Volume 1 of Decline and Fall was published in 1776.