I have to agree with Kobbs Hessler. Ron Clarke was the first man under 28:00 in the 10,000 with a 27:39.4. Insane.
From the Sports Illustrated account of the race:
The weather was comfortably cool but the track only moderately fast when Clarke and two others, Jim Hogan of Ireland and Claus Boersen of Denmark, jogged up to the starting line for the 10,000-meter run. Clarke immediately jumped well out in front of the other two, perhaps prompted by his prerace announcement that he intended to set some world records. Running alone and paced only by the cheers of 21,000 Norwegians, not a word of which he could understand, Clarke sped past the blinking timers stationed at the six-mile mark in 26:47, lowering a 17-day-old record (set by Billy Mills and Gerry Lindgren at the National AAU championships in San Diego) by a thumping 24.6 seconds. At the end of another 376 yards Clarke burst through the 10,000-meter tape in 27:39.4, reducing his own world record for that distance by an even more astonishing 34.6 seconds.