re: Mike Richards: Archaeological evidence for Sodom and Gomorrah
The first of the "five cities of the plain" mentioned in Genesis, of which Sodom and Gomorrah were two, was discovered at Bab edh-Dhra, Jordan in 1924 by William Foxwell Allbright, but only later found to be an Early Bronze Age city. Four other Early Bronze Age settlements have since been found in a line southward, though they have yet to be excavated. Despite further searching, only five settlements of this period were found, corresponding the the "five cities of the plain".
Evidence that the settlements were destroyed by fire and not resettled for two thousand years has been found at Bad edh-Dhra and at least one of the other sites.
Also, the destruction of Sodom was discussed by many classical writers, including the Greek geographer Strabo and the Roman historian Tacitus in the 1st century BC. Both stated that the story was widely believed, and that the remains of the cities could still be seen. According to the Jewish historian Josephus, writing in the 1st century AD, "... there are still marks of that Divine Fire, and the traces of the five cities are still to be seen, as well as the ashes of their growing fruits; ... [which] if you pluck them ... dissolve into smoke and ashes. So what is told about the land of Sodom is confirmed by the evidence of our eyes."
Source: "Ancient Mysteries" by Peter James and Nick Thorpe, ISBN 0-345-43488-9