No parades, sirens or speeches marked the moment two years ago when a plane slammed into the US defence headquarters. At 9.37am inside and outside the building, people simply stood in silence and remembered what had happened.
Little evidence is left of the gaping hole ripped in one of the Pentagon's five outer walls on 11 September 2001 when hijackers deliberately crashed American Airlines Flight 77.
All work at the Pentagon stopped at 9.37am
One stone - blackened from the fires of that day - remains from the original wall while the rest of the damaged area has been completely rebuilt, pristine under a cloudless sky that reminded many of two years ago.
It was there that a handful of military and civilian personnel came outside for their own personal commemoration.
And the low-key but respectful atmosphere spread throughout the immediate area.
The traffic appeared to stop on the highway that runs beside the Pentagon, though that was probably just the remnants of the Washington morning rush-hour. The roar of take-offs from nearby Reagan National Airport also seemed to be halted for the minute's silence, though again that could have been coincidence.
But the construction workers on the grounds of the Pentagon downed their tools, took off their hard hats and bowed their heads as 9.37am approached.
The massive American flag that once shrouded the destruction has gone, but a smaller banner was rigged to a makeshift flagpole at a construction office, flying at half-mast.
The official ceremonies were planned for earlier at Arlington National Cemetery and later inside a new chapel at the site of impact where four stained glass windows, partly put together by survivors, were unveiled.
It was far removed from the other crash sites at Ground Zero in New York and a meadow outside Shanksville in Pennsylvania.
Unlike in Lower Manhattan, the Pentagon stayed open and operational even in the immediate aftermath of the attack which killed 125 people in the building and 59 passengers and crew on Flight 77.
And more than that, Pentagon personnel had a central role in reacting to the 11 September attacks, planning the invasion of Afghanistan and overthrow of the Taleban and subsequent operation in Iraq, now dubbed the front line in the war on terror by President Bush.
Pentagon operations continued even as the building smouldered
But even if the building has been repaired and the people inside keep doing their jobs as they did before, there are of course those for whom the memories are still fresh.
Navy Lieutenant Sherma Saif, a dentist, had just finished treating a patient on the far side of the Pentagon when he heard the announcement that there were many casualties.
He had not heard or felt the impact of the crash and thought maybe medical personnel were being asked to help with injured people from a bad traffic accident.
When he saw the destruction, he reassessed what help he could give - covering the wounds of a badly burnt young serviceman, then rolling on wet ground as he went repeatedly into the burning building to rescue those trapped inside, staying at the site until the early hours of the next morning.
He continued to work at the Pentagon with all its memories up until about six weeks ago when he was posted elsewhere.
But he went back for the second anniversary and was surprised that his emotions were just as raw.
"I wanted to come back. I wanted to see it face to face, it helps," he told BBC News Online.
"When I came through the door today, I had to pause and just look at the building. I did it subconsciously, the images of what happened just came right back to my mind."
The stench of the jet fuel and destruction which hung around for weeks afterwards has now gone but survivors see reminders all around where others just see new walls and more construction.
"That's the ridge where I sat and watched the Pentagon burn," Lieutenant Saif said.
There are no graves to tend at the Pentagon - its dead are interred at nearby Arlington.
But there was a sense of hallowed ground there on the anniversary, as construction workers stood side by side with military men and as the sound of a funeral bugle drifted over from the national cemetery.