Exchange Flags is a Grade II listed building in Liverpool, England. It is laid out in a 'U' shape, with Walker House situated on the west side and Horton House on the east side. Walker House (formerly known as Derby House) was adapted during its construction to include a reinforced bunker that housed the Western Approaches Command Headquarters, the command centre for the campaign waged against the German submarine fleet during the Second World War. The courtyard faces Liverpool Town Hall and contains the Nelson Monument.