In what half of the 16th century was the castle that overlooks the river that flows between Glenbuck and Crossford built? built?
River Nethan: The River Nethan is a river which flows between Glenbuck in East Ayrshire and Crossford, South Lanarkshire where it feeds into the River Clyde, with the town of Lesmahagow and surrounding villages sitting on the river course. Craignethan Castle:  Built in the first half of the 16th century, Craignethan is recognised as an excellent early example of a sophisticated artillery fortification, although its defences were never fully tested.
the first half