There's a quality to old photographs that's so sentimental and romantic - especially if they are not your own. I found an old sandwich tin full of photos ranging from 1940 to the 1980's at a car-boot sale last weekend. I think the fact you don't already link the pictures to familiar mundanaties of everyday life ("oh, that's just another one of Grandad's picnics") means you immediately get some sense of romance and mystery - the photo above is a great example. Where are they? Why are they there? When was the last time you actually wandered across the tarmac with your suitcase - it must have been taken some time ago. Were they rich? Even famous? Perhaps they're on their honeymoon. Perhaps they robbed a bank the day before.
See the more of the photos here.