The red sandstone castle stands on a rocky outcrop at the neck of the Severn's loop, guarding the landward approach to the town. It was founded by Roger de Montgomery in 1074, expanded by Edward I, and used as a military headquarters during various Welsh campaigns. By the Tudor period it was already falling out of use as a fortification, though it remained a symbol of royal authority in the Welsh Marches.
Today the castle houses the Shropshire Regimental Museum, which covers the military history of the county from the 18th century to the present. The castle itself is worth visiting for the views from the Laura's Tower (named for Telford's daughter) and from the walls, which give a panoramic view over the town and the Severn's bend. The castle grounds are pleasant to walk through and open without charge during the day.