If you are into superlatives, here are two dealing with anechoic chambers. The acoustic anechoic chamber has an absorbing surface and is shielded from the outer world in order to investigate sound waves with all reflections being removed (more recently there are radio frequency anechoic chambers as well). The experience visiting such an anechoic chamber at Harvard University in 1948 and hearing his own blood pressure and nerve system instead of silence led John Cage to the famous statement: “until I die there will be sounds. And they will continue following my death. One need not fear about the future of music.” The most quietest place on earth is, according to the Guinness Book of World Records, the anechoic chamber of Orfield Labs in Minnesota, Minneapolis, while the biggest anechoic chamber of the world is the Benefield Anechoic Facility at Edwards Air Force Base, California. I imagine what Cage would have said if the anechoic chamber he had seen at that time would have been a facility “to support ground testing of electronic warfare systems on full-scale aircrafts such as the B-1B and B-2 bombers”… Thanks to Unidentified Sound Object for the link.