I haven't done any proper exploring in a while, although when we were camping last week we found an old castle just up the road from where we stayed. Loch Doon Castle was originally on an island but was moved, brick by brick, after water levels in the loch were raised in the 1930s. There's not much left of it now but considering it was first built in the late 13th century I'd say it's doing ok!
Has anyone been? It was so warm the day we went, we pretty much had a quick explore then dashed back to the air conditioned car! Ah summer.