Scarborough is not only a strong castle by nature and by art, but is capable of containing several thousand men,—in fact, a small army. South of Scarborough, also upon the coast, but where the natural advantages of the cliff had to be supplied by enormous earthworks, was Skipsea, held and strengthened by Drogo, William’s Flemish lieutenant in that country. Aldbrough was also a Holderness castle, built by Odo of Aumarle, of which there remain only the mound and the wall. Between Scarborough and York stood Malton, a seat of Earl Siward, and held by David of Scotland against King Stephen. The masonry is now gone, but the site is still marked by the Roman camp within or upon the edge of which the castle stood. North of Malton is Pickering, once the burh of the English Morcar, where are the remains of a shell keep upon the mound. Here the mound is central between and common to both wards. The general enclosing curtain is tolerably perfect, and the whole affords an excellent example of the manner in which the Norman architects dealt with an earthwork when the mound stood in the centre of an enclosure, instead of as usual upon one side of it. On the edge of the Honour of Pickering is Hamlake or Helmsley, the seat of the Barons de Ros before they inherited Belvoir, and where the remains of a very late rectangular keep stand on one side of a rectangular court, having two regular gatehouses, walls built against lofty banks, and beyond them strong and extensive outworks in earth and masonry. It is difficult to form an opinion upon the age of these earthworks. They impinge upon and are certainly later than a small Roman camp. At Mulgrave and Normanby were castles; at the latter are still parts of a rectangular Norman keep. Mulgrave stands on the sea cliff. It was the seat of the Saxon Wada and afterwards the Castle of Nigel Fossard and the Mowbrays. At Gilling some early vaults and walls are worked into the later castle of the Fairfaxes. Thirsk, Black Bourton in Lonsdale, and Malzeard, the “capita” of three Mowbray Baronies, all contained castles of some importance in the twelfth century. Of Malzeard and Bourton the earthworks are considerable. Tadcaster, a place of strength both in Roman and Danish times, possessed also a Norman castle, of which, however, only the mounds remain; and there is even less of Hugh Puisèt’s work of Northallerton, surrendered to Henry II. in 1174, and ordered to be destroyed in 1177. Its earthworks are intersected by a railway. Of Tanfield, a Fitz-Hugh and Marmion castle, there are still some small remains.