My '100 year old house' example was to point out that _even_ for a 100 year old houses Americans care a whole lot. I think ajmurmann here is talking about older archeological findings.

Regarding digging, you might find it funny that Indus valley civilization got discovered thanks to their bricks that the British found while laying railway tracks in North Western India. Those where being used as free and cheap but high quality ballast. So its indeed true in some regions one has to take care to miss.