The Old Customs House is an historic Sydney landmark near Circular Quay and believed to be on the site of the First Fleet Landing and flag-raising in 1788. It contains parts of the oldest surviving building of its type in Australia, and has been used continuously since its construction in 1844-45.

It served as the headquarters of the Customs Service until 1990s when it was granted by the Commonwealth to the City of Sydney and became a venue for exhibitions and private functions. Refurbished in 2003, it is now home of the City of Sydney Library.

The Customs House embodies the work of three successive and individually distinguished government architects: Mortimer Lewis, James Barnet and Walter Liberty Vernon.

The ground floor features a 4.2m x 9.5m scale model of the Sydney CBD, seen through a glass floor. The model weighs one tonne and was built by Modelcraft in 1998. Historic photos and documents of the various stages of the building are also displayed.

The Customs Service was responsible for imports and exports, excise on locally manufactured goods, immigration control, and illegal drugs and publications.

In June 1990 the Customs Service were relocated. The instigator of the original sandstone building was Colonel John George Nathaniel Gibbes, the Collector of Customs for New South Wales for a record term of 25 years between 1834 and 1859. The original, two-storey Georgian structure was designed by Mortimer Lewis and featured large windows to afford a clear view of shipping activity in Sydney Cove.
Gibbes also built Admiralty House at Kirribilli which also commanded views of shipping on the Harbour.

Special Features of the current library

• A ground floor magazine salon in a lounge room setting
  
• The largest range of local and international newspapers in an Australian public library
  
• Access to high quality databases
  
• Internet and email access
  
• 32 public access computers and 4 scanners
  
• A multimedia wall hosting exhibitions and Sydney information
  
• The Grand Reading Room located on level 2
  
• Exhibition and cultural programs in the new venue spaces
  
• Free Library tours for students groups: Thursdays at 10am - No bookings required.
  Meeting point - ground floor lobby (lounge area).
  Tour takes approximately 30 minutes. No tours on public holidays and December 15 to January 15.