In this photo of runners crossing the finish line before the explosions, you will see the big, blue framed monitor against the red, brick building:
Shortly after the bombs:
Where is the monitor??? Proof that the bombings were filmed days earlier as a drill and spliced into the marathon day to run as a continuous shot.
Here's the original link with larger photos.
There should no longer be any questions about this. Now let's move on to more false flags and hoaxes.
Stay alert and stay well.