The picture shows the sealing of the CMS Tracker as it was before the start of the LHC Run2. The shot was taken right below the beam-pipe (visible in the top center of the image) where the proton bunches travel to collide each other just few meters away inside the Tracker. A support of the beam-pipe is visible just in the center below the pipe, the sealing also wraps the CMS Calorimetry all located inside the Solenoid, visible in the corners, that is about six meters in diameter which gives away the actual diagonal size of the picture.