Photographs of men who fought in the Revolutionary War. They were young when they fought in the war for our independence, and survived into old age, in time for photography to be invented. It's very humbling to look into the faces of these men who gave so much for us. It reminds me of the time I saw a traveling Smithsonian exhibit that had George Washington's sword and scabbard. As I looked at them and thought about the first president actually holding them in his hands, I realized I'd never visualized the reality of history before. George Washington was a name, but I hadn't ever imagined him as a flesh and blood human being.
In a similar vein, the last person alive who was born in the 1800s was closer to the signing of the Constitution (1787) on the day of her birth (1899) than to the present day. And to reiterate, she's still alive.