[1] The Post and Telegraph Office was closed in late 1889 to become the South Brisbane Mechanics Institute and Library.

[1] About 1897, the council with the help of a government subsidy built the corner structure and the complex became known as the South Brisbane Municipal Library and Technical College.

[1] Architect George David Payne was employed to convert the former library to the Randall Art Gallery and extend the concert hall and supper room.

The two-storeyed former Post Office and Library both have Stanley Street frontages, similar gable roofs and string courses that delineate the two floors.

The front facade has multi-paned windows, a pair of faceted bays and raked verandah roof supported by large timber brackets.

[1] The third stage (1902), at the rear, is a long rectangular building with light coloured horizontal strings and window arches.

The interior walls has timber panelled dados, plaster raked ceilings and an unadorned proscenium stage.

The former South Brisbane Library is significant historically for its importance as the former Post and Telegraph Office, mechanic's institute, technical college, library, art gallery, and concert hall of South Brisbane, and remains a tangible reminder of civic identity.

It is also significant as a marker of the former alignment of Stanley Street, the main commercial thoroughfare of South Brisbane in the late 19th and early 20th centuries.

Despite internal refurbishment, the former concert hall remains important in illustrating the principal characteristics of an early 20th century auditorium designed to address the warm Queensland climate.

The building demonstrates a visual cohesiveness, despite having been constructed in several stages to the designs of at least three architects, and makes a significant landmark and aesthetic contribution to the historic precinct centred on South Brisbane Memorial Park.

[1] The place has a special association with the life or work of a particular person, group or organisation of importance in Queensland's history.