Complex sentence: An axial banking hall (Telling Room) behind the building, designed by John Dick Peddie, was added in 1857; it features a domed roof, painted blue internally, with gold star-shaped coffers.
Split into simpler sentences: An axial banking hall (Telling Room) added behind the building, designed by John Dick Peddie, was built in 1857. It features a domed roof, painted blue internally, with gold star-shaped coffers.