The Dollis Brook Viaduct, also known as the Dollis Road Viaduct, Dollis Viaduct or Mill Hill Viaduct, is a railway viaduct to the west of Finchley, North London, United Kingdom. It carries the London Underground's Northern line from Mill Hill East station to Finchley Central station. It is the highest point on the London Underground above ground level, reaching nearly 60 feet (18 m).