The FBI had a para-military squad stationed at the base of the Washington Monument. They were quite vigilant, though one suspects behind the bullet-proof vests and high-tech gadgetry they might have felt a tad ridiculous. The plaza was closed to all others. What scenario were they here for? At what point would they leap to action? I think an unattended bomb is more likely than an insurrection. And as for the Washington Monument, the government should just auction off the top level to the highest bidder for the duration of the concert. Have the police, the military and rescue squads at the ready, but keep public areas open to the public, unfenced and unfettered.
We Are One: Opening Inaugural Ceremonies at the Lincoln Memorial. Washington, DC.