New York Times article

The last paragraph is a hammer blow.

"BEFORE it moves into a new office tower in downtown Manhattan, Salomon Brothers, the brokerage firm, intends to spend nearly two years and more than $200 million cutting out floors, adding elevators, reinforcing steel girders, upgrading power supplies and making other improvements in its million square feet of space.

The work, which began last month at Seven World Trade Center, reflects both the adaptability of steel-framed towers and the extraordinary importance of fail-safe computer and telephone systems for the brokerage industry. According to many real estate experts, no company has ever made such extensive alterations to a new office building in Manhattan.

...

In some office buildings, that alteration would be impossible, but Silverstein Properties tried to second-guess the needs of potential tenants when it designed Seven World Trade Center as a speculative project.

''We built in enough redundancy to allow entire portions of floors to be removed without affecting the building's structural integrity, on the assumption that someone might need double-height floors,'' said Larry Silverstein, president of the company. ''Sure enough, Salomon had that need. "