The Holborn Viaduct–Herne Hill line is a railway line between Holborn Viaduct in the City of London and Herne Hill in the London Borough of Lambeth. After the closure of Holborn Viaduct station the line ends at the south portal of Snow Hill tunnel merging into Snow Hill lines. From there the Widened Lines to St Pancras and Kentish Town are reached. Today the section north of Blackfriars is part of the Thameslink core. Originally being a branch line of the London, Chatham and Dover Railway (LCDR) towards the City of London, the line is sometimes called LCDR City Branch.