The Concorde did it's "Ice Testing" at Moses Lake, Washington, USA in 1975. There were two full flight and maintenance crews. One English, one French. The English guys seemed to be Dicks but the French we met were cool. They invited my brother and I to the airport to take a look. We walked under, around and through. The cockpit was astoundingly complex. Like you said, it was an absolutely beautiful object.

Why Moses Lake? A way underused 15,000 ft (4500m) concrete runway, the Cascade mountains just west and very small population to complain about the sonic booms. I got to see it land/take off at least 10 times. It was even more beautiful in flight if that makes any sense. The drop nose made it look like a stork.