Photo by darkday shared under CC BY 2.0

Photo by darkday shared under CC BY 2.0

Photo by kris krüg shared under CC BY-SA 2.0

Photo by kris krüg shared under CC BY-SA 2.0

Photo by Bogdan Suditu shared under CC BY 2.0

Photo by Bogdan Suditu shared under CC BY 2.0

Photo by Leonardo Rizzi shared under CC BY-SA 2.0

Photo by Leonardo Rizzi shared under CC BY-SA 2.0

Photo by NASA/Joel Kowsky shared under CC BY-NC 2.0

Photo by NASA/Joel Kowsky shared under CC BY-NC 2.0

Burning the Midnight Oil

Photo by Miria Grunick shared under CC BY-NC-SA 2.0

Fireworks

Photo by Florian Ferfer shared under CC BY-NC-SA 2.0

Photo by Niall Kennedy shared under CC BY-NC 2.0

Photo by Niall Kennedy shared under CC BY-NC 2.0

Measure of security

Photo by Brian Talbot shared under CC BY-NC 2.0

EMP Video Wall

Photo by Sean Davis shared under CC BY-ND 2.0

Light trail

Photo by AshtonPal shared under CC BY-NC-ND 2.0

Tunnel_Cage

Photo by Timothy Vogel shared under CC BY-NC 2.0