Kilometre zero

Kilometre zero, also known as zero mile marker or zero milepost, is a particular location from which traveled distances are traditionally measured. Historically, they were markers where drivers could set their odometers to follow the directions in early roaming guide books.

One such marker is the Milliarium Aureum of the Roman Empire, believed to be the literal origin for the maxim that "all roads lead to Rome".

Source: Wikipedia