artillery observation tower

observation point / observation post (OP)

conning tower

control tower

control tower operator

watchtower (watch tower)

strut tower

aerodrome control tower

lighting tower

vertical access tower

watch tower

launching tower

secondary armament director tower

parachute tower

radio tower

forward observer (FO), forward observation officer; (artillery) observer / spotter

artillery observation post

artillery observation unit

field artillery observation battalion

forward artillery observation point

anti-aircraft artillery observation aircraft

artillery group observation post

artillery groupment observation post

artillery instrumental observation

artillery observation

artillery observation aeroplane

artillery observation aircraft

artillery observation helicopter

artillery observation plane

artillery observation post vehicle

artillery observation tank

artillery observation vehicle

artillery reconnaissance and observation