The first time I went down to see Kes, we popped over to Avebury for a wee look at the West Kennet longbarrow. It is undoubtably the oldest man made structure I've been in. It was started in around 3600BC and was used for around 2500 years. It was at one time filled to the roof with bits of pottery and and all sorts of odds and ends that gave archaeologist a field day (probably a field year or two) but you can now go in quite a long way to a burial chamber or one of the side chambers - it's really quite a magical place.
The entrance is protected by slabs of sarcen stone.
Not quite so old, but perhaps the second oldest structure I've been in is the Broch that I saw with Bev a year or so earlier while on a tour of the highlands. It's close to Loch Duich on which Eilean Donan castle stands and since it's ridiculously picturesque, a quick shot of the castle first.
It seems that the history of brochs is open to a certain amount of argument as to whether they were a fortified building or built to impress. I don't know and I certainly didn't come here to argue. The earliest ones date from 500 to 200BC and they were built up until about the 1st century AD. They are made from two drystone walls one inside the other with cupboard space and stair cases inside the cavity. Our one, and I think most did, had a second floor when it was in use. This one is not the easiest to find, being a couple of miles up a rough road and another 10 minutes or so on foot to reach but it is well worth it - there are other easier to reach brochs and in much better condition than this one here.
and a cow