Contained inside the walls of Carlisle Castle, this new museum explores the county's proud military history, with weapons, medals, standards, uniforms and other artefacts associated with the region's regiment – from its beginnings as the 34th Regiment of Foot in 1702 through to its current incarnation as the Duke of Lancaster's regiment. The flagship exhibit is a reconstruction of a WWI trench, a full-blown audiovisual experience.
You don't have to pay for entrance to the castle if you just want to visit the museum.