The Lockheed SR-71 "Blackbird" aircraft -- likely the greatest aircraft every designed and made by man. Designed at the Lockheed 'Skunk Works' by a team headied by Clarence "Kelly" Johnson, likely the greatest aircraft designer ever.
Capable of flying at over 85,000 ft (more than 16 miles high), at mach 3+ (over 2,200 mph).
Los Angeles, CA to Washington, DC in 64 min 20 sec, avg speed 2,144.8 mph (1990 - its retirement flight on the way to a museum in DC)
New York to London: 1 hr, 54 min. 56.4 sec (1974) -- your average Boeing 747 flight time is about 6 1/2 hours.
Enough numbers: check the Wikipedia page and any number of other SR-71 pages for photos and info.
This aircraft -- and others like the U-2 -- were tested out of the ultra-secret area just northwest of the Nevada Test Site (nuclear test site), usually named 'Area 51'.
This site is still the most secret and hidden area in the USA if not the world. You can check that out on Google too, but beware of UFO weirdos.
Check the Wikipedia page http://en.wikipedia.org/wiki/Area_51
and the independent 'Dreamland Resort' page at http://www.dreamlandresort.com/ for real info.
Since more than 50 years have passed since the start of many of these projects, much has been declassified, and the people sworn to secrecy under penalty of treason are now free to tell stories, and many of those still alive are delighted to finally be able to do so.
It's hard to even understand today the level of secrecy and paranoia surrounding all of this, nuch of which continues.
During the development and testing of the SR-71 (the successor to the U2 which proved vulnerable to anti-aircraft missiles, when pilot Francis Gary Powers was shot down over Russia), no one without a 'TOP SECRET' government clearance was allowed to work on, consult on or even view this aircraft. Even the Groom Lake (Area 51) base personnel without such a clearance were locked in windowless rooms such as their living quarters, when the aircraft was even being momentarily outside. Testing and flights occurred at night, so that Russian (and American) satellites could not photograph the aircraft. And on and on...
Now, one former test pilot for the program has told a great story of one of his flights:
On a test flight of an early, prototype version of the SR-71 flying from Groom Lake toward California, the aircraft suddenly became uncontrollable, flipped upside down and was not recoverable. The pilot ejected safely, and the aircraft crashed.
Uninjured, the pilot (back in his regular USAF uniform the next day) was in a cafe just across the border in California, when a couple of 'good 'ol boys' in a long bed pickup truck pulled up, parked and approached him. They said something like, "Hey, we got your aircraft here." What they had recovered and had in the back of their pickup was the cockpit canopy from the crashed aircraft. At this time, NO ONE without a top secret security clearance had EVER seen even a part of this aircraft. The pilot told them they could not say anything about this to anyone, ever, and told them that the aircraft had a nuclear weapon on board (everyone knew about and was paranoid about this in the 1960's). They agreed, and hung around the cafe while the pilot called his command and the California Highway Patrol, who arrived to confiscate their pickup and hold it until the USAF could arrive to take custody of the aircraft part. Then the FBI arrived on site and took the guys away to their main office in Sacramento, interrogated them, polygraphed them, and had them swear to and sign National Security agreements not to mention any element of any part of this incident, under penalty of treason.
(A treason conviction carries the death penalty and the FBI made sure they understood that this would be the case.)
After that, the FBI took the pilot into custody, interrogated and polygraphed him, and then asked if he would agree to being questioned under 'truth serum' (sodium pentothal). He agreed, of course, since if he refused he'd lose his security clearance and thus his job.
He says in his memoir, that he doesn't remember anything the FBI asked him or what he answered, although it must have satisfied them, but it got him into real trouble with his wife.
The FBI just brought him home, carried him into his house and dropped him on the sofa in the living room. He was still so drugged and 'out of it', his wife assumed that he had just gone out and gotten drunk. :)
PS: as of the time of writing, he and his wife have been happily married for more than 60 years.