What do you mean "discovered"? I may be confused, but I thought we're talking about hundred-year-old houses? In Greek cities, there are villas that are 100-150 years old and beautifully built. We aim to restore those, as they're beautiful buildings and nice reminders of an earlier era, but they are thought of as "almost modern". Ancient stuff is anything that's more than two thousand years old or so, and those definitely have higher significance (although you can barely dig a hole without finding a bunch of those too).

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.