My grandparents are old (mid to late 90s) and still have an incredible memory. I find their descriptions of the world they grew up in to be fascinating. Some examples:

* his amazement when he learned that somebody had received a radio signal that was bounced off of the moon

* he worked on a trans atlantic ship in his teenage years during prohibition, and had his first beer in Germany at the age of 16

* depression era job prospects

* walking home from a "picture" after his car was stolen, he and a few friends heard his horn (which was somehow identifiable). They were track runners, so they ran down the car and it turns out it was a young guy who had just borrowed it to go visit his girlfriend, and was on his way to return it.

* his godfather was a civil war vet