Deeper down into the building, the floors grew darker where windows had been replaced by plywood panels in advance of dismantling. Here, floors were punctuated with open shafts ringed by wooden barricades.  All the floors visited last week, from 23 to the last vestiges of 27, had already been certified as clear of potentially hazardous contaminants and ready for deconstruction, said Avi Schick, president of the Empire State Development Corporation and chairman of the Lower Manhattan Development Corporation, which owns 130 Liberty Street. That was true of the 20th through 22nd floors, too, he said.  The corporation had expected to have the 18th and 19th floors certified as early as tomorrow.  But it was the 17th floor — off limits to visitors — where the fire was presumed to have begun. That would have presented a dreadful and confusing scene of a much different kind to the firefighters who arrived there on Saturday.  “You think you’re going to open construction floor plates,” Mr. Schick said, “and instead you’re going into a house of horrors.”  The 17th floor was in the midst of being scrubbed, scraped and vacuumed by workers in hazardous-materials suits. Thick plastic barriers lined the walls, cutting down on the light coming in from the windows.  Firefighters would have had to contend with decontamination stations, constructed of plywood, through which workers pass on their way to and from clean floors. These have two or three air-lock chambers, divided by thick plastic curtains.  “You come off the hoist and you immediately confront these series of curtains, like a maze,” Mr. Schick said. “If you go left, it’s a dead end. If you go right, you have to keep opening curtains, one after the other.”  Adding to the problem, he said, were exhaust systems installed on the contained floors to maintain “negative pressure” — that is, they keep the air pressure inside lower than it is outside, so that if the protective barriers develop a leak, contaminated air will not be expelled.  But the exhaust systems would also have brought in outside air that fed the flames and would have drawn smoke across the floors without fully venting it, since their filters are designed to trap particulate matter.  “It might, unfortunately, have been the perfect storm of misfortune,” Mr. Schick said.  A visit two years ago, before the demolition began, found a building in which time stopped on Sept. 11, 2001, and never started again.  Before the interior cleanup and decontamination began in earnest, there were enough traces of Deutsche Bank and of Bankers Trust, which constructed the skyscraper, that one could feel the presence of its occupants.  Smoothie prices were still posted in the fourth-floor cafeteria. Mailbox cubbyholes on the 39th floor were still set aside for P. David, J. Gary, R. Livermore, M. Mongello, F. Rivera and J. Robinson. One of Michael Philipp’s calling cards — “Member of the Board of Managing Directors” — could be spotted on the 34th floor.  No one returned to work at 130 Liberty Street after 9/11. The building was too badly damaged by the collapse of 2 World Trade Center. But as the traces of Deutsche Bank’s hasty, unplanned exit were removed and as the building itself cast a shorter and shorter shadow on ground zero, it seemed as if the awful spell had at last been broken.  A version of this article appears in print on , on Page B1 of the New York edition with the headline: From an Imposing Bank Tower to a Battered ‘House of Horrors’. Order Reprints| Today's Paper|Subscribe
Once a 41-story skyscraper, 130 Liberty Street has seemed foredoomed since the days immediately after 9/11 and almost jinxed in the years since then.