A listed historic building is a structure that has been officially recognised and designated as possessing special architectural or historic interest, thereby granting it legal protection. This designation is assigned by the relevant heritage bodies, such as Historic England, Cadw (in Wales), Historic Environment Scotland, or the Northern Ireland Environment Agency. Listed buildings can range from grand mansions and castles to modest cottages, churches, bridges, and even public structures like telephone boxes or milestones. The listing process identifies and celebrates buildings that are significant due to their architectural design, construction methods, historical associations, or contribution to the character and heritage of a particular area. Buildings or structures can be listed under different grades, reflecting their level of importance: Grade I: Buildings of exceptional interest, representing some of the most significant examples of their kind. Grade II*: Particularly important buildings of more than special interest. Grade II: Buildings of special interest, warranting every effort to preserve them. Once a building is listed, it becomes subject to legal protection, meaning that any alterations, extensions, or demolition work that could potentially affect its special character or historic interest requires prior consent from the local planning authority.