I once found a pile of old photos that had spilled out of a rubbish bin in a quiet suburban street in Athens.
After we had finished laughing, and after poking around in the bin for the rest of them, we realised that we had a family's entire history in our hands. 
From a photo of the port of Pireaus just after it had been decimated by the retreating Nazis, through pictures of a couple getting married in the 70's, to holidays in the Redwoods in California, with them posing proudly next to a ford Capri and ending up with an old couple sitting quietly holding hands in an Athenian park, we had their entire lives in our hands.
It was a very touching moment. And they had just been thrown out.
As if they meant nothing.
I treasure the pictures I kept. I didn't know them, but in some small way their memory lives on in a way it wouldn't have if we hadn't drunkenly stumbled across them.
I learnt so much about the country I love from that pile of randomly discarded photographs.