Cathays Library is a free public library endowed by Andrew Carnegie and built in 1906-7 by Speir & Beavan, architects of Wharton Street, Cardiff. The sculpture is by T. A. Jones of Cardiff, the stained glass is by Harvey & Ashby of Birmingham, while the contractor was W. T. Morgan of Cardiff. The unusual butterfly plan echoes contemporary Arts and Crafts designs by E. S. Prior and W. Lethaby and is one of the earliest examples of such a plan form in Wales. The library was designed with a central lending section and well-lit outer wings housing children's and adult 'reading halls', with separate ladies' reading room adjacent to the lending section.

It is a symmetrical single-storey Arts and Crafts Gothic style library built of coursed rock-faced stone, Bath stone dressings and slate roof. It comprises of a low faceted entrance range set diagonally between higher pavilion-like outer wings aligned at right angles respectively to Whitchurch Road and Fairoak Road. The central entrance has double panelled doors flanked by buttresses and has a segmental-headed doorway with 3-light small-pane overlight incorporating coloured glass. A panel within the parapet above the doorway is engraved with a dedication and is flanked by shields engraved 'AD 1906'.

It is listed grade II* as an especially accomplished and well-preserved Arts and Crafts design, utilising a corner site in an original manner, and for the additional special interest of its pioneering butterfly plan. Its group value with Gladstone schools provides historic integrity to the Cathays townscape.

Source:- Cadw listed buildings, NJR 21/01/2009