By Nick Childs BBC Pentagon correspondent

The first of the workers whose offices were destroyed or damaged in the 11 September terrorist attacks began moving back in on Thursday.

It was an important symbolic day for the Pentagon; it may have been just a couple of dozen people, and they were still unpacking boxes and waiting for some of their furniture.

But these first few workers were reclaiming their workplaces - offices that have been rebuilt and strengthened.

The plan now is for all the reconstruction work to be completed by the end of the year.

Narrow escape

One of the workers was Peter Murphy, a senior legal adviser to the head of the US Marine Corps.

It's very emotional for me, because it's a reminder of what happened, of the 180 people who were killed

Returning worker Peter Murphy

He was in his fourth-floor office, just a few metres from the point of impact on the day the American Airlines jet struck.

He got out just before the office collapsed completely.

He is back there again, just waiting for his desk to arrive.

''It's very emotional for me, because it's a reminder of what happened, of the 180 people who were killed,'' Mr Murphy said.

''On the other hand, I think it's a great job, and a fast job that the contractors have done, and the Pentagon renovations folks have done. I think it's truly amazing.''

The Pentagon wing had to be fully demolished before rebuilding

It has been a massive undertaking, first to demolish the damaged wing of the Pentagon, then rebuild it.

One improvement since the attacks is the installation of illuminated strips and arrows along the bottoms of the walls, rather like the floor-level lighting now familiar in airliners, to guide people out in an emergency.

Hundreds more workers are expected to move in over the next few weeks.

All the offices on the outer ring of the damaged ring, nearest the point of impact, should be reoccupied in time for the first anniversary of the attack.

The rest of the work should be finished by the end of the year, some two months ahead of schedule.