This is the ruined 14th-century stronghold of the Black Douglases. The seven-story tower was built between 1639 and 1690 by Archibald the Grim, Lord of Galloway. In 1455, Threave was the last Douglas stronghold to surrender to James II, who employed some of the most advanced armaments of his day (including a cannon similar to Mons Meg, the massive cannon now displayed in Edinburgh Castle) in its subjection. Over the doorway is the gallows knob from which the Douglases hanged their enemies. In 1640, the castle was captured and dismantled by the Covenanters, the rebellious group of Scots who questioned the king's right to make laws.
To reach the site, you walk .8km (1/2 mile) through farmlands and then take a small boat across the Dee. When you get to the river, ring a bell signaling the custodian to come and ferry you across. The last boat is at 6pm. For information, contact Historic Scotland, Longmore House, Salisbury Place, Edinburgh (tel. 07711/223-101; www.historic-scotland.gov.uk).