Bomb planted in a bathroom on the Senate side of the Capitol building

The bomb was planted by members of the Weather Underground. "I don't regret setting bombs," Bill Ayers said when interviewed by the New York Times on the occasion of the release of a book he'd written. Asked by the interviewer, Dinitia Smith, if he would do it over again, he blamed "the violence of the Vietnam War."

That interview, coincidentally, appeared in the paper the last time the Capitol was targeted for attack by a radical group, thankfully unsuccessfully: Sept. 11, 2001.