The Town Hall was built in the 1880s on the site of an old cemetery from local Sydney sandstone in the grand Victorian Second Empire style, and has been described as having "lavishly ornamented composition with focal tower and fanciful roofs". It remains the only non-religious city building from the era to retain its original function and interior. The building houses the Sydney City Council Chamber, reception rooms, the Centennial Hall and offices for the Lord Mayor and elected councillors.

The Centennial Hall (main hall) contains Sydney Town Hall Grand Organ, the world's largest pipe organ with tubular pneumatic action, built from 1886 to 1889 and installed in 1890 by the English firm of William Hill & Son. This organ possesses one of only two full-length 64' organ stops in the world (the Contra-Trombone in the pedal). Before the opening of the Sydney Opera House and its Concert Hall, the Town Hall was Sydney's premier concert hall, and many notable performances took place there.

Built between 1869 and 1889, it is one of Sydney's most elaborate buildings, a remarkable feat considering it was created by a succession of architects who strove to outdo each other with their own individual ideas of what the end result should be. The first was RJ Wilson who was replaced initially by Albert Bond when Wilson s design proved impractical. Bond completed the vestibule with its crystal chandelier, stained glass windows and ornate plaster work; the Bradridge brothers added the clock tower in 1884 and three other architects were employed to complete the Centennial Hall with its coffered zinc ceiling and mighty 8,500 pipe organ.