The mere mention of Fort Knox usually means the gold vault. Officially, it is the U.S. Bullion Depository and was constructed in 1936 at a cost of $560,000. But this structure has been surrounded by more legend, mystery and myth than perhaps any other building in America.

Look but don’t touch is one way to describe it. But you could get chased off if you stare at the building too long.

With a reported $100 billion in solid gold stacked in the lower level of the gold vault, it is no wonder the U.S. Treasury keeps a tight lid on the inner workings of its security system.

The grounds are surrounded by three fences that some say are electrified. Armed guards are positioned in bunker-like structures at each corner. Reinforced gates and barriers have been added since the Sept. 11, 2001, attacks to further discourage anyone from wanting to get close. They are authorized to use deadly force if need be. Combine this with alarms, cameras and possibly land mines, and you have a facility that would be nearly impossible to breach.

Of course, the government makes no comments regarding the gold vault’s security. In other words, it’s not what we know, but what we don’t know that helps keep the building secure.

There are, however, some known facts about the gold vault. The actual structure that can be seen from the highway is 42 feet high and 121 feet wide, and the vault door in the lower level is 21 inches thick and weighs more than 20 tons.

Paul Urbahns, a historian from Radcliff, said the security climate has drastically changed since the gold vault was built.

“In the beginning, the local newspaper published the gold delivery schedule,” he said. “The gold arrived on trains, and the locals would go to the railroad siding to watch the gold being loaded onto trucks. The area was lined with armed military for security until the gold arrived at the gold vault.”

In the early days, anyone caught trespassing would have been arrested. Today, they could be shot. It was reported several years ago that a helicopter with a Travel Channel film crew flew over the gold vault. Flying low and using telescopic lens, they were arrested when they landed in Louisville. Their film was seized.

Perhaps nothing drew more attention to Fort Knox than the 1964 James Bond film “Goldfinger.” Movie villain Auric Goldfinger planned to break into the gold vault. He didn’t want to steal the gold but wanted to render it useless by making it radioactive, thus inflating the value of the gold he already had.

Thank goodness for agent 007 and his ability to halt the evil scheme and preserve our nation’s financial stability.

You can rest assured that none of the movie’s scenes were shot inside the vault, and any information about its inner working was conjured up in Hollywood. Several scenes were shot in and around the Radcliff-Muldraugh area as well as some involving actual uniformed soldiers at Fort Knox.

As security conscious as the gold vault is, it is said to be the third most photographed building in America, behind the U.S. Capitol and the White House. The actual day-to-day responsibility for protecting the nation’s gold supply falls under the jurisdiction of the U.S. Mint Police.

Gaining inside information about the Gold Vault is like, well, breaking into Fort Knox. It’s nearly impossible. Believe it or not, I was able to wrangle a phone number to a guard post inside the building. After one question, the guard courteously but quickly referred me to the U.S. Mint Public Affairs Office in Washington, where I was told to submit my questions in writing, which I did.

By most accounts, Franklin D. Roosevelt and Harry S. Truman are the only U.S. presidents to have visited the gold vault. However, the written response from the U.S. Mint was that “Roosevelt is the only president to have signed the visitors log book at the Fort Knox Bullion Depository.” Of course, that doesn’t necessarily mean Truman didn’t visit. He just may not have signed in.

When asked if any biological warfare strains were kept in the gold vault, the written response was no.

In the 1970s, rumors began to circulate that the gold vault had depleted its inventory. “A writer suggested there was nothing in the vault,” said former U.S. Sen. Walter “Dee” Huddleston, an Elizabethtown resident. “He wrote that France had called in all its debts, and all the gold had been returned.”

So in 1974, Huddleston, several congressional delegates from across the country and 100 handpicked journalists got to do what no other group had done before or since – go into the gold vault and look around.

Gerald Lush at the time was a young editor for the News-Enterprise in Elizabethtown, and he was among some of the locals selected.

“It was covered by national and state newspapers, magazines, radio and TV,” he said. “I really didn’t think that much about it at the time. It was a fun experience, but I didn’t see it as significant back then.”

Now, Lush wishes he had some of the photos snapped that day. “They just disappeared from the files at the newspaper,” he said.

Still, Lush has etched in his mind what he saw.

“I remember the rich, yellow glow when they opened the vault,” he said. “I had been told that gold didn’t glow after it was stored for a period. But the gold I saw glowed.”

Bill Evans, a radio executive in Elizabethtown also saw gold.

“I saw several rooms full of gold, from top to bottom,” he said.

Evans also recalled something else.

“Four or five of us in the group were standing around talking,” he said. “The guards were behind us with Thompson submachine guns. We could tell they were nervous when one of them clicked his bolt and jacked it. They were all under stress while we were there. I realized my visit there was something very special even then.”

Huddleston recalled that after the tour he presided over a news conference set up at the gold vault.

“I told everyone there was gold in the vault, and lots of it … from the floor to the ceiling,” he said with a laugh. “They made an exception for us to go in, and it hasn’t happened before or since.”

I grew up in Elizabethtown a few miles from Fort Knox and have my own memories and recollections of the gold vault.

I lived next door in 1954 to William L. Jenkins, who was in charge of the guards at the vault. I can remember him leaving for work each day with a thermos under his arm. He would drive to a nearby parking lot, where he would meet other guards who lived in town, and they would all get into a tan station wagon and head off to Fort Knox.

I don’t remember ever having any conversation with Jenkins, other than waving and saying hello. After all, I was just 11 years old, and that’s pretty much the way adults and kids interacted.

I remember my family sitting in our living room watching TV as our neighbor, Jenkins, stumped the panel on “What’s My Line?”  It was nice knowing that this person appearing on a popular television show was my neighbor.

A few years later, I was playing golf at Lindsey Golf Course, the officer’s course at Fort Knox. One of the holes ran beside the vault property. My golf ball somehow ended up there. I could see the ball, only a few feet out of bounds. All I had to do was take two giant steps and retrieve it. Signs were posted to “KEEP OFF” and “STAY OUT.” But I had paid 25 cents for the ball, and I was going to get it. One step onto the vault property brought out a booming voice commanding me to “HALT.” It scared me so bad I almost gave up golf.  I wonder what happened to that golf ball?

— Gary West’s column runs monthly in the Daily News. He can be reached by emailing west1488@twc.com.