A few years ago I bought an album of old french postcards themed around prehistoric monuments and natural rock features.
This sparked a short obsession with prehistoric postcards. I bought most of them from ebay and boot sales, setting myself the challenge of paying no more than a pound or two for each card. The obsession burned itself out after a year or two so and I decided to put the collection online for anyone to use. I uploaded about a third of the cards and then kind of lost interest. I’ll return to it one day and finish the job.
If this sort of thing interests you, the collection can be found here