The Golden Age of Rome was around 2000 years ago, when Christ was born. It's population peaked at 1,65 million souls around the year 100. From the on the Western Roman Empire started to decline and as early as the 5th century the Western Roman Empire had declined so much that the year 476 is generally accepted by historians as the end of  the Western Roman Empire. Population by then had declined to around 50.000. The Empire continued it's leagacy in the Eastern part, but from Constantinopel, which is the city of Istanbul today. Rome has always been a seat of the Holly Pope, but with a population of 17.000 in 1347 it was hardly important. But Italian cities gained independance during the Middle Ages. Rome was able to grow during the Renaissance and after becoming the capital of a unified Italy in 1871 Rome gained importance.