The present Lambton Castle[13] stands on the site and incorporates portions of the original building of Harraton Hall, a manor-house erected about the year 1600. Very considerable additions were made to this hall by William Henry Lambton, grandfather of the late Lord Durham, from designs by the elder Bonomi, in the Italian style. The first Lord Durham also made considerable alterations and additions to the building from plans furnished by Bonomi, the general appearance of the mansion being entirely changed. The south front is in the Tudor style and castellated, and the north is Norman.
The great hall is panelled, and the windows are glazed with richly stained glass, containing a representation of "Ye Legend of the Worme of Lambton," and also the heraldic emblems of the family. The dimensions of the hall are 94 feet by 36 feet, being larger than St. Stephen’s Hall, Westminster. The principal staircase leading out of the hall, communicating with the upper apartments, is 24 feet wide and 36 feet high. East of the hall is the dining-room and west is the drawing-room, abutting on the terraces of the west lawn.
Owing to the subsidence of the hill on which the castle stands, through some old colliery workings underneath falling in, the castle had become, when the second Earl succeeded to the estates, insecure. To meet this, and strengthen the foundations, the workings, two seams deep, round the castle, to the extent of 4½ acres, were filled up with débris. Three seams lower still were bricked up, over 10,000,000 bricks being used, and in several instances in the fourth seam the brickwork exceeded 30 feet in height.
Hilton Castle, like Lambton, stands on the north bank of the River Wear, on a gentle slope commanding an extensive view of the valley to the west.
The present building, a melancholy-looking tower, is only the gatehouse of the original castle. It is first mentioned in the inquisition post-mortem of William de Hilton in 1435, when it is described as "a house constructed of stone, called the Yethouse." The intention of the original builder, the William just mentioned, was evidently to erect an extensive mansion on a similar scale, but there is sufficient evidence to show that he never completed the work.
That there were other buildings probably surrounding a courtyard is proved by various inventories. In 1559, after the death of Sir Thomas Hilton, an inventory of his effects mentions the great chamber, the green chamber, the middle and new chambers, the gallery, the wardrobe, the parlour, the chamber over the hall door, and various out-buildings, such as the brewhouse, buttery, and the barns. The tower is mentioned separately, and the term evidently applies to the existing building.
These surrounding buildings were probably removed by John Hilton, who early in the eighteenth century built
Old Tower at Ravensworth Castle.