antenna
architecture
army
base
blue
border
boundary
building
cabin
camp
concentration
control
convoy
dark
detention
eerie
evening
facility
frontier
guard
guardpost
high
hill
industrial
jail
light
lookout
military
night
observation
old
outpost
patrol
penitentiary
post
prison
protection
safe
safety
security
stand
station
structure
surveillance
tower
view
warning
watch
watchtower