Not on display
Finberg does not specify which particular ‘ruin’ this may show, but a number of possibilities occur when this is compared to other sketches. It may, for example, show the ruins of Dunbar Castle from the west sitting on rocks that descend like a staircase into the sea. Similarly, the ruins of Fast Castle, that sit on a rocky headland jutting out to sea have a similar appearance (see, for example, the Dunbar sketchbook of 1801, Tate D02736; Turner Bequest LIV 78a). A sketch on folio 38 verso of this sketchbook (D13388; CLXV 38a) also resembles these rocks, and this introduces the possibility that the sketch may in fact be of the fortifications of Bass Rock. Without more of the landscape in view, it is impossible to certain which subject it shows. Turner concentrates on the outline of the structure with a few economical lines to indicate windows and the shape of the rocks.