A historic building, and imposing building. You can imagine it looking out over the port of Sydney (if you can equally imagine the absence of the Cahill Expressway). A large diorama of the Sydney area which you can walk over is on display in the foyer. The Sydney City Library occupies the building, and sometimes has exhibitions. Free.

Customs House is a heritage-listed museum space, visitor attraction, commercial building and performance space located at Circular Quay in Sydney, New South Wales, Australia. The building served as a customs house prior to Federation and then as the head office of New South Wales operations of the Government of Australia agency Department of Trade and Customs (and its successors) until 1988. The customs function relocated to a new site in 1990. The initial designs were by Mortimer Lewis and it was built during 1845 by under the administration of Governor Sir George Gipps. It is also known as Customs House (former) and Site of former Customs House. The site was added to the Commonwealth Heritage List on 22 June 2004; and to the New South Wales State Heritage Register on 2 April 1999.

Ownership was transferred to the City of Sydney Council in 1994, when it became a venue for exhibitions and private functions. After being refurbished in 2003, it has also become the new home of the City of Sydney Library. The ground floor of the building houses a 4.2-by-9.5-metre (14 ft × 31 ft) scale model of Sydney's city centre viewed through a glass floor. The model was built by Modelcraft in 1998 and weighs one tonne. Images of the various versions of the building across its history are also displayed on the ground floor.