Theatr Twm O'r Nant, including forecourt walls and railings

Theatr Twm O'r Nant is a late-Victorian single-storey hall designed in a municipal classical style. It is constructed of brick with rendered main elevations and features stucco quoins, topped by a hipped slate roof. The building originally has a symmetrical five-bay facade with a central entrance bay. This entrance bay features an advanced distyle portico supported by columns with fluted collars in the Adam style. The portico is adorned with a heavy dentilated pediment that includes a finely-dentilated and moulded cornice extending onto the main elevations, and it is topped with a panelled parapet. At the corners of the portico are two ball finials on pedestals, which are also repeated on the corners of the hall.

Within the pediment, there is a heraldic carved and polychromed cartouche displaying the Royal Arms of Queen Victoria. The entrance itself is arched and has double doors, each consisting of five moulded panels. Above the entrance, a circular oculus features an archivolt extending from the entrance architrave, complete with projecting keys and imposts. Flanking the entrance are four tripartite sash windows, with the outer windows set in slightly recessed bays. These windows have large central sections and narrow flanking sections, all topped with moulded cornices supported by outer consoles, and are framed by panelled architraves with bracketed sills. Each window is also adorned with a stucco pediment. Notably, the window on the far right has been converted into a panelled door in recent years, with its upper section blocked. The side elevations consist of two bays with windows similar to those on the front.

Surrounding the building is a square forecourt enclosed by low limestone rubble walls topped with dressed copings and simple railings. The section facing the road features a pair of limestone ashlar gate piers at the center, each with a moulded cornice and banded ball finial, along with similar piers at the right and left corners.

The interior was not inspected at the time of the survey.