abandoned
alcatraz
alcatraz island
architecture
barb
barbed
barbed wire
blue
border
brick
building
california
captivity
cloud
confinement
construction
crime
criminal
detention
facility
fence
forbidden
freedom
gaol
guard
house
imprisoned
inmate
jail
lock
lookout tower
mobile phone
outdoors
photography
prison
prison tower
prisoner
protection
punishment
security
sky
steel
surveillance
tower
vertical
wall
watch
watchtower
window
wire