The remains of the Castle can be visited
Smailholm Tower

Smailholm Tower, a castle ruin in the Scottish Borders, is a fortress that once served as protection against raids.
History+
Smailholm Tower was built in the 15th or early 16th century by the Pringle family, who held the lands of Smailholm as followers of the Earl of Douglas. The castle was typical of Scottish Peel Towers and provided protection against English attacks. It was attacked by English troops in 1543, 1544, and 1546, with the garrison of Wark Castle plundering the castle in 1546. In 1640, Sir Andrew Ker of Greenhead successfully defended the tower against the English. Later, the complex came into the possession of the Scott family, who rebuilt parts of the tower and the barmkin wall. In the 18th century, the tower fell into disrepair after the family moved to nearby Sandyknowe. In 1950, the ruin was handed over to state care by the last owner, the Earl of Ellesmere, and was restored in the 1980s.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Maciek Wegrzyn
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 55.6042, -2.5764