Nest of collared doves.
This nest was built several years ago, between a stone house wall and a Sky TV antenna. Not a sensible location, as the birds are fairly easy to see - if of course you know where to look.
I had no idea that the doves were currently nesting, and was working close to the antenna. Suddenly two adults flew away, leaving these two eggs. My camera was close at hand so I took this photo. The doves came back soon, hardly unruffled by this encounter.