Workers at Merrill Lynch in downtown New York do not need the viewing platform which was installed to give day-trippers a better glimpse of Ground Zero. They need only look out of the window.
On Wednesday the investment bank reopened another set of offices in its building at No 2 World Financial Center, to the west of what was once the World Trade Center, and welcomed back 1,200 staff. A ceremony to mark the occasion included rousing turns from mayor Michael Bloomberg, New York state governor George Pataki and a video address from President Bush who paid tribute to the "spirit and determination" of the bank.

But the event, ending with a rendition of God Bless America, failed to stir at least one worker, an office administrator in her early 40s called Ilene, faced with the bleak prospect of walking to work past the gaping hole where the twin towers once stood. She used to have a desk facing the site but asked to be moved.

"It's just depressing," she said. "It's very painful to have to walk past this every day and remember the people who were lost - especially if you were here on September 11. I had just come out of the subway when the second plane hit.

"It's just incredible, you look across and you can see Century 21 [a famous local department store] which you couldn't see before."

The clean-up of Ground Zero is ahead of schedule but there are still mounds of rubble revealing twisted iron girders. More than six months after the terrorist attacks, bodies are still being carried out and the messages to missing loved ones remain pinned to walls and fences around the area. Huge sets of floodlights stand outside the Merrill Lynch building to illuminate the site at night. Maps can be useless because many streets are still cut off.

Homecoming

It is not difficult to see why the visiting dignitaries invested the Merrill Lynch homecoming with such significance. Estimates from Tenantwise.com, a New York real estate agency, suggest that 59,000 jobs have been lost from the lower Manhattan area as companies fled. That, despite rents dropping to $30 (£20) a square foot - almost half the price of midtown Manhattan. The vacancy rate downtown has doubled since September 11.

"Some people are leaving because of the psychological effect of what happened, for security reasons, for environmental or transportation reasons. The really shocking part is that companies are paying more for office space elsewhere just to leave," said Tenantwise chief executive Myers Mermel. "This could have a great impact on New York as a financial capital."

The devastation that rained down during the terrorist attacks was not limited to the World Trade Center. As well as the six destroyed blocks, at least 12 of the 23 buildings damaged remain closed. The future of many, badly scarred by falling debris and fires, remains uncertain.

A landmark building on 90 West Street, put up in 1907, was ablaze for days. An open gash down its side overlooking Ground Zero reveals buckled floors and office interiors.

One of the most severely damaged sites was 130 Liberty Plaza, owned by Deutsche Bank, which is covered by a dark shroud of gauze to prevent rubble from falling on to the streets below. It has a 20-storey scar on the north face. Deutsche remains uncertain whether the building can be saved.

At Merrill Lynch, 1,422 windows needed refitting and 2,200 pieces of granite were replaced on the facade, enough to build a three-foot wide pavement from there to the Empire State Building.

Some things have improved. When the bank moved staff back into the less damaged No 4 World Financial Center in October, the company's medical director had to brief staff on the latest findings on asbestos and other airborne hazards. The bank also had to subsidise four ferry routes to carry staff to work because subways were closed. By the end of April, Merrill Lynch hopes to have moved 8,500 people back. Merrill Lynch chief executive David Komansky said the return was a milestone. "Six months ago our world changed for ever but we have been working hard to recover, to heal and moved forward together."

The hope is that the lower end of Manhattan will keep hold of its status as the world's premier financial district. But there is evidence that some of the big banks are leaving.

Morgan Stanley, which lost six people in the attacks, is planning to move some staff to upstate New York, having decided to reduce its vulnerability to disaster by not concentrating its people in one area. Goldman Sachs already had a 1.2m sq ft building under construction in Jersey City where it will move several thousand dealers from downtown New York.

Lehman Brothers, which had been Merrill Lynch's neighbour, hopes to have all 6,000 of its staff in a building north of Times Square within months. "We had to find somewhere large enough to house our staff that had the right facilities for an investment bank and where the timing was right," said spokesman Jason Farago.

Part of the problem downtown is that many of the buildings unaffected do not fit the requirements of a modern investment bank. "What we need in place of the World Trade Center is a bigger, better, super-sized Canary Wharf as well as new and improved infrastructure," Mr Mermel said.

"The bulk of realty stock downtown is 70 to 80 years old - buildings that don't work for modern companies, which is the same problem the City of London has."

Others on their way out of the area include Bank of America, which occupied the first tower and is moving into new premises in midtown. Cantor Fitzgerald, the broker that suffered such terrible losses, is heading in the same direction. Nasdaq is moving its entire operation to Times Square.

Recovery workers at the World Trade Center site are reported to be planning a ceremony to mark the end of the excavation work in May. But progress is unlikely to be rapid. The subway, for instance, will need first attention. The Lower Manhattan Development Corporation, which is run by former Goldman Sachs partner John Whitehead, hopes to present its initial plans for the site next month.

Memorial

The corporation is working with Larry Silverstein, who in an epic piece of bad timing leased the twin towers from the Port Authority just weeks before the attacks and now faces a legal battle with his insurers.

The received wisdom is that there will be four smaller 50-storey towers as well as retail, theatre and museum space on the 16-acre site. There will also be a permanent memorial.

In recongition of the departure of much of the financial community, the site will include more residential space and the LMDC is wooing biotech companies in the hope of creating a new hub to sit alongside the investment banks that remain.

Officials at Battery Park City, the largest downtown residential neighbourhood, said the occupancy rate had climbed to 76% from 60% last autumn.

"We've made a lot of progress so far and Merrill Lynch moving back in is an example of that," Mr Whitehead said. "There is no question in my mind that New York City is the world financial centre. It has been damaged by the events but certainly not destroyed. We have many anchor organisations including the New York Stock Exchange, the Federal Reserve Bank and companies like Merrill Lynch. Things are moving in the right direction.

"There has been a trend of companies moving out of lower Manhattan for sometime. But Wall Street is still Wall Street and it always will be. And $30 is better than $50 uptown - that will attract people back." The new buildings would be "more beautiful" than the towers. "Certainly no one ever claimed beauty for the twin towers."

How far the character of downtown changes will be determined as other financial institutions decide whether to follow Merrill Lynch and move back. That it will have changed is in no doubt.