@Pkrd has it, this is x-arm of the Advanced LIGO gravitational-wave detector in Hanford, WA (well, the concrete cover around the beam tube, at least).
The 200 area of the Hanford nuclear reservation is on the horizon. Fun fact: the 200 area is one of the most radioactively contaminated places on Earth!
The 200 area of the Hanford nuclear reservation is on the horizon. Fun fact: the 200 area is one of the most radioactively contaminated places on Earth!