|   | TANK TRAP * | Reinforced concrete blocks, walls or ditches designed to obstruct the progress of a tank or armoured vehicle. |  | back | 
		|   | SITE * | Unclassifiable site with minimal information. Specify site type wherever possible. |  | back | 
		|   | CANAL * | An artificial navigable waterway used for the transportation of goods. Nowadays also used for recreational purposes. |  | back | 
		|   | RIDGEWAY * | A road or way along a ridge of downs or low range of hills. |  | back | 
		|   | DEFENCE * | This is the top term for the class. See DEFENCE Class List for narrow terms. |  | back | 
		|   | BRIDGE * | A structure of wood, stone, iron, brick or concrete, etc, with one or more intervals under it to span a river or other space. Use specific type where known. |  | back | 
		|   | PILLBOX * | An often squat building with thick, loopholed walls and a flat roof, designed to accommodate a variety of weapons, usually strategically positioned to cover a vulnerable point in a defensive system. Many were built to standardized designs. |  | back | 
              
              
                
                    * Copyright of English Heritage (1999)
                    