When the Lockheed Martin Skunk Works began marking its 70th birthday this year, media specialist Bob Driver dragged an old suitcase into a company director’s office. Opening it, he asked if the contents could finally be shown to the public.

Inside was a 55-year-old model of the A-3, Lockheed’s first try at blending stealth with speed—and a direct predecessor of the triple-sonic A-12 Blackbird. It had been designed by Skunk Works founder Clarence “Kelly” Johnson, and Driver had hidden it away for decades, defying periodic management directives to purge company archives.

The director he approached was Stephen Justice, who runs Advanced Systems Development at Skunk Works. “I treasure that the people here want to protect our history,” says Justice. “Bob recognized the A-3 model as being something special, and important to hold onto.”

Seventy years earlier, Kelly Johnson had stood on a desert lakebed in California and grinned as an XP-80 screamed past him on its maiden flight. Seven months before that, he had walked out of U.S. Army Air Forces General “Hap” Arnold’s office with a contract to design what became the first U.S. jet fighter to see combat. In just 215 days, 23 handpicked engineers built it in a drafty hangar so awash in the fumes from a nearby factory that wags started calling it the Skunk Works.

Justice began canvassing program managers for other artifacts and documents that could be released to honor the anniversary. The objects in this gallery had never before been seen by anyone without a security clearance.

Why so much secrecy? “It takes about one-tenth the time and one-tenth the resources to develop a countermeasure to anything that’s introduced,” Justice says. “To maintain your edge over any threat, you need to protect what your capabilities are. And sometimes you need to protect their existence.”

Today’s Skunk Works employs 3,700 employees at facilities in Palmdale, California, Marietta, Georgia, and Fort Worth, Texas. They are working on over 500 projects, from radar coatings to war games to compact fusion reactors to a Mach 6 spyplane.

Sifting through the archives revealed breathtaking technologies and capabilities. Some were too early for their time; some cost too much; some filled a need that didn’t yet exist. But everywhere, Justice says, “you see clear examples of the creativity and unbounded imaginations of the grandfathers of the Skunk Works.”