Hadrian's Wall Path near the site of Milecastle 78
Milecastle 78 was first located and partially excavated in 1934. Only the west wall was examined in the excavations and was found to be 2.8 metres wide. One course of masonry stood upon the inner face; the outer face had been robbed. The excavators did not record whether remains of the earlier turf and timber phase of the milecastle survive.
The milecastle was investigated again in 2000 as part of the Milecastles Project. Trenches were excavated across the west, south, and east walls of the milecastle. The stone milecastle measured approximately 19.2 metres east-west, and 20.7 metres north-south externally. The foundations of the walls were 2.5 metres wide. A burnt feature, possibly a hearth or oven, was found in the southwest corner. No evidence for the Turf Wall milecastle was recovered.
Each milecastle on Hadrian's Wall had two associated turret structures. These turrets were positioned approximately one-third and two-thirds of a Roman mile to the west of the Milecastle, and would probably have been manned by part of the milecastle's garrison. The turrets associated with Milecastle 78 are known as Turret 78A and Turret 78B.
Turret 78A (Kirkland) (grid reference NY24316175) lies 20 metres northwest of Kirkland farm-buildings in the line of a hedge on the south side of the road. It was identified in the 18th century by the antiquarian John Horsley. The location was confirmed in a trial excavation in 1948. There are no remains visible above ground.
Turret 78B (grid reference NY24076226) has never been accurately located. Tradition records a mound or tumulus close to its calculated position, and it is claimed that an upright stone (possibly a Medieval cross) once stood there. There are no visible remains of a turret, mound, or stone.
- Historic England, "Hadrian's Wall and vallum between the access road to Glendale caravan park and the track south of Kirkland House in wall miles 77 and 78 (1014701)", National Heritage List for England, retrieved 19 December 2013
- Historic England, "Milecastle 78 (10134)", PastScape, retrieved 19 December 2013
- Historic England, "Turret 78A (10137)", PastScape, retrieved 19 December 2013
- Historic England, "Hadrian's Wall north of Kirkland House, Port Carlisle in wall mile 78 (1016075)", National Heritage List for England, retrieved 19 December 2013
- Historic England, "Turret 78B (10129)", PastScape, retrieved 19 December 2013