The doors on the Western Hangar on Pembroke Dock's dockyard were kept firmly locked during the spring of 1979, with workers sworn to secrecy.
They were building the Millennium Falcon, the iconic spaceship in the Star Wars film The Empire Strikes Back.
The town is now celebrating its links with the "fastest hunk of junk in the galaxy".
The top secret Millennium Falcon project was given the code name The Magic Roundabout.
It also lends itself to the name of the community arts film which premieres not in a galaxy far far away, but in Pembroke Dock's Pater Hall on Saturday.
It tells the story through the adventures of a group of children who stumble across the secret spaceship, and features interviews with the men who built it.
Sharron Harris, from Curious Ostrich Productions, said: "It's a fascinating story.
"You'd think everybody in Pembroke Dock would have known about it, and I'm surprised very few people did."
The 10 minute film, which features some unseen photographs, was inspired by a song local musician Andy Brindley had written about the Millennium Falcon.
"The community really came on board," said Ms Harris.
"Our last film took three days, but this one took about a year as we got totally embroiled in people's stories and everyone from 80 year-olds to children wanted to be in it."
Code Name Magic Roundabout will be shown at 19:00, 20:00 and 21:00 GMT.
Jeff Waterman, whose stories inspired the script for the film, was part of the team which built the Millennium Falcon.
He said: "It all started with a friend of mine coming to my house one night and asking if I wanted a job. Knowing him as a prankster, I asked what sort of job?
"He told me he was building a spaceship and that I should meet him at the dockyard.
"Into the hangar I went and there it was in front of me.
"It was all steelwork and it was our job to cover it with plywood and timber and make it look like a spaceship."
Once complete, the Millennium Falcon was transported to studios in Hertfordshire, where The Empire Strikes Back was being filmed.
When the film was released the following year it was a box office smash, and so too was the 1983 film Return of the Jedi.
This was to be the last time the spaceship featured on the big screen.
A Pembrokeshire town's "best kept secret" is the subject of a new community arts film.