Urban icons were common in the Roman world, with monuments, cityscapes and personifications all used as metonyms. Yet an icon for the most important city of all is not easily identified. Rome was always sui generis, too large to be easily captured visually. Filled with innumerable wonders, no single structure or artwork stood for the whole. Representing the collective, as well as the great extent of the empire, the city could not be encapsulated in a single image.