abstract
apartheid
auschwitz
barb
barbed
barbwire
barrier
black
border
boundary
camp
chain
concentration
concept
crime
danger
electric
fence
freedom
gate
genocide
germany
gray
guard
history
intrusion
iron
isolated
jail
memorial
metal
military
poland
prison
protection
razor
safety
security
shape
sharp
sky
steel
symbol
trespassing
war
white
wire