Treharris Public Library

This is a public library, dating from the early 20th century, constructed of red brick and Bath stone with a slate hipped roof, originally surmounted by a cupola which is now missing. The site is steeply sloped, resulting in a single-storey front and a basement to the rear. The front has three bays, with the outer bays projecting and gabled, featuring moulded copings. The gables have channelled ashlar outer piers with modillion cornices and a top blocking course, and contain large, fine Palladian windows with Ionic columns, a moulded arch, keystone, and coloured leaded glass. A sandstone plinth is present, raised on a tolled Pennant stone base on the right side due to the slope. Cast-iron rainwater pipes descend to a central piece, which features a modillion cornice that projects forward over an ashlar section with a parapet lettered "Treharris" between two ashlar blocks. There is a blocking course on each side, along with an ashlar frieze bearing the words "Free" and "Library" carved into either side of a motto, topped with an oak-leaf decoration above a shield depicting the Virgin Mary holding a spear and two swords, above the main entrance hood. The elaborate ashlar segmental curved hood is moulded with a panelled soffit supported by large brackets with acanthus carving, and carried on bulbous Ionic columns. A very large iron clock, framed squarely and serving as a memorial to the First World War, projects from the hood. The tympanum beneath the hood holds a roundel cartouche decorated with sprays on either side, above a broad doorway with two iron gates. Four stone steps lead up to the entrance, flanked by low, curving iron rails and low, sandstone moulded walls. Small, paired windows with single ashlar sills and lintels with dripstones are located on either side of the entrance. The main entrance door is recessed, the recess having a mosaic floor with the letters "CL" in a wreath (referring to the Carnegie Library). An Art Nouveau plaque records the building’s opening. The double doors have bevelled glass and a large overlight with some panes shaped.

The left end of the building is roughcast, with flush stone heads and sills to the windows. It has four bays, with a door in the third bay. Windows and the overlight of the door have coloured leaded glazing. The right end wall is plain rendered. The rear basement is rendered and has a pebbledash first floor, with two windows on the left, three in the centre, and a Palladian window on the right; most of these windows have coloured leaded glazing.

Inside, the left reading room has a curved plaster ceiling and leaded Palladian windows at each end. A curved wall, formerly behind the main entrance, features a seven-light window with patterned leading. The former entrance lobby has a moulded cornice.