Blackcastle, an ancient camp in Greenlaw parish, Berwickshire, on a precipitous bank at the confluence of Faugrist Burn and the Blackadder, 1¾ mile NW of Greenlaw. An entrenchment commences opposite to it, on the right bank of the Blackadder; runs about ½ mile along the bank; turns thence to the S in the direction of Hume Castle; and, in the southerly reach of it, is called Black Dikes.

(F.H. Groome, Ordnance Gazetteer of Scotland (1882-4); © 2004 Gazetteer for Scotland)