There are many churches in the South that have picnic tables out in the churchyard for gatherings. They're made of granite, with a giant slab for the tabletop.
These aren't that old, but you can find them much older if you drive around in the country for a little while. I'm thinking of starting a photographic collection of them.
My question to you is - what about the rest of the country? And if you live in a country besides the US, what about there? Is this a common sight in your neck of the woods?