Does 'In many other places, the ancient sites lay buried'and still do'beneath modern  modern property owners quite understandably take a dim view of tearing down their buildings on the off chance that the remnants of an ancient town will be found several yards below.' exist in a separate context from 'All ancient places have been investigated. ', without logical interdependence?
In many other places, the ancient sites lay buried'and still do'beneath modern  modern property owners quite understandably take a dim view of tearing down their buildings on the off chance that the remnants of an ancient town will be found several yards below.###All ancient places have been investigated. 