The Braid is Ballymena's combined arts centre and museum, housed in the refurbished town hall on Castle Street in the town centre. The museum side holds a permanent collection of local history — archaeology, social history, items relating to the linen industry that once drove the economy of mid-Antrim — alongside a programme of temporary exhibitions. It's a modest but well-presented local museum rather than a major attraction, and an hour is enough to take in the permanent collection.
The arts centre side runs a programme of concerts, theatre, and cinema. If you're spending more than a night in Ballymena it's worth checking what's on, since it pulls in acts from across Northern Ireland and occasionally further afield. The building itself — an early twentieth-century municipal hall — is attractive, and the café on the ground floor is one of the better options for a coffee in the town centre.
Named after the River Braid that flows through the town, the building also serves as a useful orientation point for exploring the town centre on foot.