You probably know it as a monument of sorts, sitting at the side of one of Wales' busiest roads.
But the stack of bricks bearing the messages "ER" and "Silver Jubilee" on the side of the A470 is not just a monument or a former chimney - but what remains of a remarkable viaduct which once spanned a valley.
The Walnut Tree Viaduct was built by the Barry Railway Company to bring coal and iron from the valleys.