Torthornwald Castle is situated in the village of that name in Dumfriesshire and is unusual in many respects. A powerful 14th century tower it stands amidst earlier earthworks, probably those of a motte and bailey castle. During the construction of the tower there was a change of plan and it was extended into an oblong from its original square - the modification being clearly visible as a race bond in the vaulting (the point at which the tower recently split).
Torthornwald provides a perfect example of what happens when a building is neglected. It was occupied as late as 1715 but fell into ruin shortly afterwards. Attempts were made to shore parts of it up in the 19th century but in vain. As late as the 1990s a complete section of the tower sheered from the main body and fell to the ground.