Rome is a city of layers.  No other city I've seen demonstrates the idea of layering over time.  It is a city that at this date is growing in all directions.  As excavations continue, the history continues to reveal itself and reclaim the spaces within the city.  Rome continues to grow as a modern city,  managing to progress with the burden of an extensive history. As I went through the city, I could think of one word to describe it, integration.  All aspects of the city seem to flow to a similar rhythm.  An example of this can be seen in the relationship between pedestrians and cars.  In the main part of the city there are relatively no stoplights for the cars.  This would seem to be terrible for pedestrians, but the opposite is the case.  The drivers seem to be willing to be somewhat subservient to the pedestrians.  Walking through the city, pedestrians have the ability to cross the streets at will.  This is true even on a six lane road.  Try that in NYC, it would never happen.  This flow and relationship between things, as far as I've seen, appears to be unique. The idea of integration also can be seen in the way Rome absorbs its tourists into its fabric such that they become a part of the city.  They do not become a negative part of the experience.