From 1961 until 1992 the U.S. government maintained a special facility in the West Virginia mountains that would have housed the 535 members of the U.S. Congress in the event of nuclear war.

"These unusual notches and a stainless steel threshold down there... There's the plate that pops off, the same over there, the slots for the pins [for the steel doors] right behind it," explains tour guide Paul Rose.

Mr. Rose is showing 30 visitors the massive steel doors that open onto a corridor leading to what was the congressional bunker. This once secret facility, five hours drive from Washington, would have protected members of Congress in the event of nuclear war.

The facility was effectively disguised as a mere addition to the already large Greenbrier hotel. Mr. Rose says construction lasted three years and began at the height of the cold war in 1958.

"Those are the same three years that they added the West Virginia wing to the Greenbrier Hotel," he said. "Great cover story as it turned out. Some expected construction out here in the middle of nowhere. The government able to slide a facility right underneath it. Nobody being the wiser.

"And I say until May 1992 because that's when this was exposed in the Washington Post," he continued. "And since the efficacy of this facility lies in its secrecy once the secret was out the government decided to close up shop and head home. It took them three years to accomplish that. Tours here began in 1995."

Secrecy was maintained despite what now seem significant clues. An interstate highway that for years led nowhere passes near to the gates of the Greenbrier. Nearby is a tiny airport with the longest runway in the entire state of West Virginia. Even the nearby rail line could have delivered the 535 members of Congress to the Greenbrier bunker.

Mr. Rose reminds his visitors that contrary to public belief this facility was never intended to be used by the President. President Dwight Eisenhower, he says, devised the plan for the bunker out of a belief that all three branches of the U.S. government needed to survive a nuclear holocaust. With the bunker in mind, President Eisenhower hosted two foreign leaders at the Greenbrier in 1956.

"It turns out that President Eisenhower was likely here for other reasons," he said. "Remember, his passion was preservation of democracy and continuity of government. To set the stage the cold war was heating up. He's seen Churchill's bunker and so on. He was especially interested in trying to protect the three civilian branches from the effects of nuclear war. The engineers had already figured out that to do that you had to carve cavities pretty deeply in granite."

The facility itself is spartan. Several dormitories with bunk beds crammed into huge rooms. One large dining room. No windows. Enough food and air to last only three weeks. The bunker of course was never used for its intended purpose. However, says Mr. Rose, it came within one hour of being activated during the Cuban missile crisis in 1962.

As the tour ends, Mr. Rose escorts his guests into a briefing room where digital clocks from various world cities are displayed next to a large mural of the U.S. Capitol dome.

"It's all digital, put in here sometimes in the 70s," he said. "Cities of interest around the planet. Moscow of course, center stage during the cold war, Baghdad up there in the upper right corner. Remember the [first] Persian Gulf war, Kuwait, 1991. Bunker exposed in 1992. That was probably the last city change in this bank of clocks."

The bunker tour has proven very popular for the Greenbrier Resort as several dozen people each week are willing to pay the 25 dollars for the two hour visit into the bunker that was never used.