When historic rocket engine parts from the Apollo moon missions go on display in May in Seattle, museumgoers will be able to compare them with an intact F-1 engine.

The 50-year-old, 18.5-foot-tall engine arrived at one of the Museum of Flight’s offsite facilities today after a road trip from NASA’s Marshall Space Flight Center in Alabama.

Just to be safe, museum spokesman Ted Huetter declined to say exactly where the rocket engine is being kept while it’s being prepared for display. “I think we’ll leave it as an ‘undisclosed location,'” he told GeekWire.

The intricately machined hardware will complement a set of beat-up components from the first-stage engines that powered Saturn V rockets spaceward during the Apollo 12 and Apollo 16 missions in 1969 and 1972, respectively.

Those engines fell into the Atlantic Ocean just minutes after launch, and lay on the bottom of the sea for decades. Finally, in 2013, salvagers backed by Amazon billionaire Jeff Bezos recovered the long-lost parts and brought them ashore for conservation in their mangled condition.

The artifacts will be the stars of the show for “Space Race,” an exhibit at the Museum of Flight that focuses on the 1960s-era Cold War contest between the U.S. and the Soviet Union. The exhibit is due to open on May 20.

The freshly arrived F-1 engine is one of several left over from the Apollo era that are being kept at Marshall Space Flight Center. When the engine is put on display in Seattle, it’ll serve as a visual guide to show museumgoers how the twisted-up F-1 components fit together in flight.

Check out these tweets documenting the engine’s arrival: