Coningsborough on the Don is the most complete English example of the Early English or Transition Norman cylindrical keep. Pembroke, though rather later, and of far inferior workmanship, is also, in its proportions and dimensions, a very fine building. Launceston, Tretower, Penrice, Skenfrith, Brunless, and Dolbadarn, are good examples, as are the Danes’ tower at Waterford, and the small and rude, but very curious, tower at Aghadoe. At Nenagh also is a very fine tower, apparently of the Early English type. The round keep of Barnard Castle, though of nearly similar pattern, is of later date. At Whitchurch, near Cardiff, are, or recently were, the foundations of a detached round tower of considerable diameter, the base mouldings of which showed it to be of Early English date. At Caldecot, a fine old Bohun castle, admirably described by Mr. Octavius Morgan, is a round tower, probably Early English, having a ditch of its own. This tower crowns a small and evidently artificial mound. It is now a mural tower upon the line of the outer wall, but it seems to have been cased, and the core is probably, or possibly, the keep of an earlier castle. Those English towers, though curious, are far inferior to those of the same period remaining in France, whether keeps, such as Étampes, 1160, the plan of which is a quatrefoil; or Roche-Guyon, where one-half of the cylinder is absorbed in a triangular spur; or mural towers, as the King’s Tower at Rouen, that at Carcassonne, and a specially fine one, lately restored, at Pierrefonds. The keep at Nuremberg is also a good example. The tower of the Louvre has long been destroyed, but its base was recently laid open, and found to contain two shafts—those of a well and a sewer. Probably the round towers, or keeps, are the oldest examples of the form, but very soon afterwards they came into use in England and France as mural towers, flanking and strengthening the _enceinte_ wall. They were especially used to cap an angle or to flank a gateway. There is an example of a round tower capping an angle, of this date, in the Tower of London, known as Bell Tower. Marten’s Tower at Chepstow is a good example of a mural tower of the Early English period, having a fine oratory attached. Its interior is a complete cylinder, but the exterior, or gorge wall, seen within the court, is flat. At Rochester, the angle of the ward next the keep has a circular tower, or rather a buttress tower, as it is not higher than the curtain. In such positions their passive strength was a great advantage.