Occupying the first floor (stair lift available) of the Carnegie Building in Market Square. The building was formerly the Brynmawr Carnegie Public Library, built in 1906. A Carnegie library is one built with money donated by Scottish-American businessman and philanthropist Andrew Carnegie. More than 2,500 Carnegie libraries were built, including many belonging to public and university library systems. The current library is nearby.

Brynmawr Museum was created by the community. Officially opened in June 2003, it is run totally by volunteers. The museum has many items of Brynmawr Furniture, made only at the Brynmawr Furniture Factory. The various artefacts donated by the community reflect the social and industrial history of Brynmawr and its surrounding areas. There are exhibits from the mining and steel industries; traditional Welsh valley culture; religious and schooldays memories and a large collection of photographs showing life through the ages.

Admission is free.