DALLAS (CBSDFW.COM) – In a building lined with memorabilia, where history can be found behind every day, there are artifacts packed away that some hope could shine light on an unsolved mystery that dates back to the Texas Centennial Exposition.

“This was not just a City of Dallas or Texas event. This was a national and international World’s Fair-style exposition,” said Jason Hays, the Vice President of Brand Experience at the State Fair.

The year was 1936. With the world looking on, fair officials knew opening day needed to be big.

So to open the gates of Fair Park, they needed a key like none the world had ever seen before.

“It was bejeweled! Extravagant. Fifty-thousand dollars worth of jewels and gold,” said Jeff Cotner, Director of Security at the State Fair of Texas.

The nine-inch-long key featured a 14-carat diamond, four strands of pearls and more than 400 other gems. “That was a piece of history – it opened the birthday of Texas,” said Hays.

Centennial Key (courtesy: Fair Park)

When the fair closed its gates that year, the jeweler who made the key, Arthur Everts, proudly displayed it in his downtown Dallas store. It stayed there for years, until it disappeared in 1952.

Sixty-seven years later, the unsolved mystery has captured the imagination of fair employees.

According to the original police report, “the world’s most gorgeous and expensive key” was “thought to have been taken from the showcase.”

But the detectives notes said he interviewed many current and former employees and had no suspects.

Everts told a reporter there were no signs of tampering on the display case, saying “everyone thought the key was in our shop having a loosened pearl reset.” But when he checked the shop, it wasn’t there.

“It’s a big missing piece,” said Hays. That’s where the investigation ends and the theories begin.

Cotner, a former longtime Dallas Police detective, has a few ideas.

“It could’ve been somebody connected to the store,” he said. “They worked up this elaborate scheme to get the item removed, and they have it in their own personal collection.”

Hays thinks it may be more innocent than that. “I could be as simple as an accident,” he told CBS 11. “I wouldn’t go, necessarily, Liam Neeson and say ‘we’re gonna come find you.'”

There’s a chance that whoever has the key now has no idea of its history. No idea, that it could unlock one of the oldest mysteries of the State Fair of Texas.

See if you can find more clues below!