A milestone is a numbered marker placed on a route such as a road, railway line, canal or boundary. They can indicate the distance to towns, cities, and other places or landmarks like mileage signs; or they can give their position on the route relative to some datum location. On roads they are typically located at the side or in a median or central reservation. They are alternatively known as mile markers, mileposts or mile posts. A "kilometric point" is a term used in metricated areas, where distances are commonly measured in kilometres instead of miles. "Distance marker" is a generic unit-agnostic term.
A mile marker on the U.S. National Road giving distances from many places
Slate milestone near Bangor, Wales
Roman milestone XXIX on Via Romana XVIII – the road linking the Iberian cities of Bracara Augusta and Asturica Augusta
Roman milestone on the former A66 between Kirkby Thore and Temple Sowerby (no inscription)
The mile, sometimes the international mile or statute mile to distinguish it from other miles, is a British imperial unit and United States customary unit of distance; both are based on the older English unit of length equal to 5,280 English feet, or 1,760 yards. The statute mile was standardised between the Commonwealth of Nations and the United States by an international agreement in 1959, when it was formally redefined with respect to SI units as exactly 1,609.344 metres.
A milestone in the City of Westminster showing the distance from Kensington Road to Hounslow and Hyde Park Corner in miles
The supposed remains of the Golden Milestone, the zero-mile marker of the Roman road network, in the Roman Forum
Edinburgh's "Royal Mile"—running from the castle to Holyrood Abbey—is roughly a Scots mile long.
Milestone on Mountbellew Bridge, erected c. 1760. Distances are given in Irish miles.