The City Circle is a system of underground railway lines located in Sydney, New South Wales, Australia that make up the heart of the Sydney underground metropolitan railway network, owned and operated by CityRail, a subsidiary of StateRail, a New South Wales government agency.
Constructed in the 1920s, the constituent stations of the Circle are (clockwise): Central, Town Hall, Wynyard, Circular Quay, St. James, Museum, back to Central.
Circular Quay was not one of the original stations on the circle. It was added later in 1956, and it has one of the best views of Sydney.
A second underground line that branches off Town Hall Station provides train services to Martin Place, Kings Cross and Edgecliff, terminating at Bondi Junction.
In the year 2000, a new privately-owned underground line, the Airport Link was opened, providing regular train services from the Circle to the Sydney Airport.
Several unused railway tunnels also exist.
