Everyone on Wall Street knows someone who has been confirmed dead or is missing as a result of last week's devastating terrorist attack. In a show of remarkable strength and unity, the lucky ones have returned to their desks, believing it to be their patriotic duty to rebuild the financial community.

These staff returned to a militarised zone with the presence of the police and the National Guard helping to ease concerns about security.

As the bankers and brokers weave their way through barricades and security checks, a stream of trucks make their way into the devastation to assist with the recovery of thousands of their colleagues.

"We are happy to be alive and to have jobs to return to," says Mr John Connorton, partner at New York law firm Hawkins, Delafield & Wood, whose office is a five-minute walk from what was the World Trade Centre. "Everybody has lost friends but there is an unbelievable spirit."

Mr Connorton explains that employees in the area believe by returning to work they are making a contribution to the recovery operation that surrounds them.

Brokerage firm Carr Futures is struggling to come to terms with the devastation that has been visited upon it. In a full-page advertisement in the Wall Street Journal it states: "As we write this letter, half of our New York colleagues are missing - along with thousands of other people. The tragedy and loss of human life is almost unbearable. Right now, our primary goal is to help each and every one of our employees and their families during this time of horror and devastation. We will rebuild our New York office - but that will come later."

The firm had the prestigious address of One World Trade Centre. Its offices were on the 92nd floor, with breathtaking views of the Statue of Liberty, New York's harbour and the Atlantic Ocean. This week, three of its employees have been confirmed dead - and 66 are missing.

"A lot of things have changed for us. To be frank, we won't do it again - be in a skyscraper. Our employees wouldn't feel comfortable," Mr Didier Varlet, Carr Futures chief executive, told the newspaper.

Locations such as the World Trade Centre made a great impression on clients. High-rise office space at the centre of the world markets has always been in great demand but, after last week's events, this is likely to change.

Companies report that employees are now timing how long it takes to get down the stairs and demanding that building operators step up security. Others just want to move away to less glamorous surroundings. The view is not so important anymore.

New York real-estate brokers say that, so far, most tenants in some of the city's tallest buildings are staying put - but are jittery. Mr Joshua Winslow, a commercial real-estate broker, is working with a tenant at the Empire State Building that wants to relocate. The firm had been considering a move before the terrorist attack but "now the firm wants out of that building and out of the path that it might fall in".

The week has also prompted a rare display of unity among bitter rivals across Wall Street.

At investment banking house Sandler O'Neill & Partners, 67 of the firm's 177 employees are missing or dead. Its founding partner, Mr Herman Sandler (57), was confirmed dead on Tuesday, while nine of its 28 partners are still missing. It joins other brokers Cantor Fitzgerald and Keefe Bruyette & Woods in the ranks of Wall Street firms devastated by the attack.

Bank of America has donated temporary offices to the firm. Three of its rivals have taken over market-making functions and are passing on the commission to Sandler O'Neill for as long as it wants, according to the head of equities at Trident, Mr David Pulliam.

"Yes, we compete with these guys. But we also have enormous respect for them and we want to see them back on their feet as soon as possible."

For others, finding an office has required some considerable effort. A week after negotiating a friendly takeover of the Sheraton Manhattan Hotel, investment bankers at Lehman Brothers have begun refurnishing its 665 rooms as offices for its 1,500 bankers and analysts who do not know when they will be able to return to their offices. Lehman's offices are at Three World Financial Centre, which was connected to the demolished World Trade Centre by a skywalk.

Another 1,700 of its employees, mostly traders, have moved across the Hudson river to Jersey City to a makeshift trading floor. From there they can see the still-smouldering ruins close to their former luxurious headquarters.

Lehman Brothers managing director Mr Jeffrey Vanderbeek says the mood of his staff is lifting each day but emotions are still raw. Business is continuing, while at the same time the firm's website carries pictures of colleagues who are still missing.

There have been logistical nightmares to contend with beyond the emotional trauma. As planes were grounded across the US immediately after the attack, many of Lehmans Brothers' senior staff were left stranded in San Francisco, where they had been attending a technology conference.

They chartered a bus and three drivers. One to drive, one to rest and one to recharge mobile phones. It made only a few stops to drop off clients along the way with one sit-down meal in Lincoln, Nebraska that had been ordered ahead as they journeyed to assist their colleagues.

The New York business community is holding daily meetings to support the recovery operation. Chief executives of the city's major corporations are offering assistance in whatever form is required, whether for the rescue effort or for those who are grieving.

Rebuilding is also discussed but in reality that is a long way off.