Expansion of City Walls
After Rome was founded in 753 B.C., the first city wall was built on the Capitoline Hill shown in light blue below. As the city began to conquer its neighbors, its population expanded and so the city walls expanded as well. (Tice, 2005)
Aside from the addition of the Vatican into the city walls in the 1600s, the Aurelian Wall served as the city boundary for almost 2,000 years and still stands today (shown below) thanks to Roman engineering expertise.