correction appended  about two weeks ago, a security team spotted scorch marks on a basement doorway below 4 world trade center, on the east side of the ruined complex, according to officials.  even in a place of mass devastation and death, those scorch marks got fast attention. they had not been noticed by a patrol team a few hours earlier, and behind the damaged -- but intact -- door were nearly a thousand tons of gold and silver. to security officials, it looked as if someone had tried to break in.  within hours, a video surveillance system was installed to keep at least an electronic eye on the precious metals until their custodian, the bank of nova scotia, had a chance to remove them. that work began this week.  a team of 30 firefighters and police officers are helping to move the metals, a task that can be measured practically down to the flake but that has been rounded off at 379,036 ounces of gold and 29,942,619 ounces of silver.  as layers of debris are peeled away, recovery workers are opening gangways to intact portions of a 16-acre basement that was largely unseen but was a place of spectacular scope in its own right. just the basement area of the world trade center enclosed twice as much space as the entire empire state building.  nearly a quarter of a mile below the spectacular vistas from the towers was their upside-down attic dropping 70 feet below the ground, a strange world with enough room for fortunes in gold and silver, for godiva chocolates, assault weapons, old furniture, bricks of cocaine, phony taxicabs and central intelligence agency files. with so many people still lost, the owners of this stuff have maintained a discreet silence during the recovery operations. but that doesn't mean they're not interested.  beneath the customs house -- 6 world trade center -- was an armada of government vehicles, including dozens owned by the secret service, in a fenced-off area. within that area was a garage where a single armored limousine was parked under the tightest security.  the limousine was so long that it needed straight-line access to the street, because it could not clear tight corners in the basement.  that car had been used to carry heads of state visiting the city, said tony ball, a spokesman for the secret service. (the president's limousines are stored in washington and flown everywhere he visits.)  in the 1993 trade center bombing, an armored secret service limousine was parked about 100 feet from a truck bomb. although the bomb crashed through five stories of concrete and the concussion destroyed cars all over that floor, the secret service limousine ''did not even have a broken windshield,'' according to a government official on the scene that day. the condition of the limousine after september's attack was not known yesterday. ''we haven't gotten anything back yet,'' mr. ball said.  asked about reports that his agency also kept what looked like ordinary taxis and telephone company trucks in the basement, mr. ball laughed. ''what i would say is that it is not unusual for law enforcement agencies to have these kinds of things,'' he said.  besides the secret service, the building named for the united states customs service also housed an office of the c.i.a.  that building is now partly collapsed, with a rubble pit 30 feet deep. somewhere in there are drugs, weapons and contraband seized by the customs service at the region's airports. the bureau of alcohol, tobacco and firearms also lost two evidence vaults, according to a spokesman for that agency, joseph green. they have not yet been recovered.  ''there could be several hundred weapons -- somewhere between 200 and 400, ranging from small-caliber semiautomatic pistols to assault rifles,'' mr. green said, adding that a few of the guns had been found. agents plan to be on the scene when the remains of the building are demolished sometime in the next two weeks, he said.  ''after that, we'll be working at the landfill to search for any important items that are still missing.''  for people who have seen the surface destruction, either in pictures or in person, it may be hard to imagine that anything is intact below ground. but engineers and recovery officials say that large parts of the underground perimeter are undamaged, even though the buildings above them are partly collapsed.  one area is below 4 world trade center, where more than two decades ago, swiss bank built a huge vault and storage area. the vault was reached from the swiss bank offices by a private elevator.  to reach the vaults, armored trucks would drive through what had once been the tunnels for the hudson and manhattan railroad, the predecessor of the path system. these tunnels had run as far east as church street, but were not needed when the trade center was built and the path terminal was set closer to the river.  the western stubs of the original tunnels, ringed with cast iron, were converted into roadways. these roads ran directly to a roll-down door in front of the swiss bank vault area. inside was a loading dock.  by the time of the 1993 bombing, swiss bank no longer was using the vault, and shortly afterward, the bank relocated its remaining operations.  the next tenant of the vault space was the bank of nova scotia, which estimated the value of the metals at $200 million.  ''we are in the process of relocating the contents of our vault at world trade center building no. 4 to another secure location, because authorities need to demolish the building,'' pam agnew, a spokeswoman for the bank, said yesterday by phone from toronto.  some of the metal is owned by the bank, and some by its customers, she said. she declined to say where the metals were being taken.  ''the contents remain safe and intact,'' ms. agnew said. ''the contents are fully insured. we're working very closely with local authorities to ensure a safe and secure relocation effort.  ''the removal of the contents was not a priority for us because we've always known it was safe and secure,'' ms. agnew said.  asked about what appeared to be an attempted break-in two weeks ago, ms. agnew said that she was unaware of it. later, she called to reiterate that the metals were safe: ''it would be factually incorrect to say there had been any attempt to steal the contents of our vault.''  however, a government official involved in the recovery efforts said that there had clearly been an attempt within the last two weeks to enter the vault area. ''it looked like they used a blowtorch, a crowbar,'' said the official, who spoke on the condition that neither his name nor his position be identified. ''the port authority police began periodic patrols, and then a closed-circuit television system was put in.''  the bank also engaged kroll inc., a security business based in new york, to supervise the relocation of the gold and silver, a process that began this week, the daily news reported yesterday.  michael cherkasky, the president of kroll, declined to comment on his company's involvement.  anyone trying to make off with the gold would not be able to run very fast: each ingot weighs 70 pounds.  photo: two brinks trucks were at ground zero yesterday to start hauling away the $200 million in gold and silver that the bank of nova scotia had stored in a vault under the trade center. (richard drew/associated press)(pg. b11)
a nation challenged: the vault; below ground zero, silver and gold