Open between April and September, the ruins of Craignethan Castle overlook the River Nethan in Blackwood to the north of Lesmahgow. It was built around 1530 by Sir James Hamilton of Finnart, and one of the earlier guests to visit the house was none other than his friend King James V. Finnart was to become a top architect and would later work for the king. The tower was well fortified, which you can still see evidence of today, such as the caponier – an unusual stone vaulted artillery chamber. The surrounding woodland is a Site of Special Scientific Interest where you might spot buzzards, sparrow hawks and kestrels.