banned
barbed
barrier
border
borderline
boundary
building
camp
captivity
cartel
construction
crime
criminal
danger
desert
enclosure
escape
facility
fence
forbidden
freedom
guard
history
industrial
jail
land
mexico
military
military area
prison
prisoner
prohibited
protection
punishment
safety
security
sky
south
spiral
steel
tower
usa
wall
war zone
watch
watchtower
wire
work
zone