The A5200 is a north-south route in central London. For much of its route it marks the boundary between the London Boroughs of Camden and Islington.
It starts on the A40 Holborn by Chancery Lane tube station and heads north along Grays Inn Road to meet the A501 opposite King's Cross Station. The northernmost section of Grays Inn Road is part of the westbound Inner Ring Road and therefore some maps mark it as part of the primary A501.
After crossing the Inner Ring Road, the A5200 runs alongside King's Cross Station before crossing the Grand Union Canal and the Channel Tunnel Rail Link. By Caledonian Park it splits owing to a one-way system. Northbound traffic follows Camden Park Road before turning right onto Leighton Road and meeting the other direction. Southbound traffic follows the straighter route of Brecknock Road and York Way.
Continuing north, the A5200 continues along Brecknock Road to end at traffic lights on the A400 Fortess Road opposite Tufnell Park tube station.
In 1922 the A5200 only ran between the A40 and A501. The section north past King's Cross Station was the B513 which ended for no reason by turning into Rufford Street. The remainder was unclassified. The A5200 was extended to Tufnell Park in the 1970s.