Edgware Road is a major road through north-west London, starting at Marble Arch in the City of Westminster (south end) and running north-west to Edgware in the London Borough of Barnet. It is also a boundary between several North London boroughs. The route has its origins as a Roman road (part of Watling Street) and therefore runs for 10 miles in an almost perfect straight line, which is unusual in London. It is part of the modern A5 road.