In green, the Servian Walls

The Servian Walls are the oldest fortifications of Rome, dating back to the city’s early stages, when settlement expanded beyond the Palatine Hill toward the north between the 8th and 6th centuries BC, joining another settlement cluster on the Quirinal Hill.
They are primarily dated to the 6th century BC. Several gates, some of which are still preserved, date back to the early 4th century BC.