President's helicopters fly over Washington, DC: Marine One

The President of the United States' helicopters (not "Air Force One," I guess) fly over Northwest Washington, DC. Probably test runs during heightened security after the Boston Marathon bombing and poisoned ricin letters reportedly being sent to the White House and Capitol Hill politician.... Plus, there is a heck of a lot of construction going on all around the District of Columbia, as evidenced by the large number of building cranes. Housing bubble anyone?