The purpose of a cast iron firebacks and used for centuries, and nearly always fitted in fireplaces, is twofold. Firstly it protects the back wall (in stone or brick) from the direct heat of the flames, and secondly the cast iron accumulates and returns heat to the room long after the fire has died down.
A genuinely decorative object, the old fireplace firebacks are usually enriched with a relief motif representing royal crowns, coats of arms, heraldic or family symbols, or stories or scenes of country or military life. At BCA, we have a large stock in different dimensions, and period styles.
Cast iron fireback, Antique firebacks
Authentic fireplace accessories such as these are important to getting an open fire to perform well, and are of course historically correct if the fireplace you are creating has to look just right.