abstract
aged
alte
article
authority
backdrop
background
barbed
barrier
black
blank
block
border
boundary
cement
cinder
concrete
cracked
crime
danger
dark
design
dirt
dirty
empty
exterior
fence
floor
freedom
front
gray
grunge
grungy
guard
imprisonment
isolated
jail
material
obstacle
prison
protection
rough
security
surface
textured
urban
wall
weathered
wire