Its remains lie near the village of Gilsland in Cumbria where it was historically known as "The King's Stables", owing to the well-preserved interior walls.

Milecastle 48 is just outside the village of Gilsland in Cumbria, immediately adjacent to the Tyne Valley railway line on its south side (grid reference NY6340666195).

[1] It had been known locally as "The King's Stables"[2] for over 100 years, but recently the heritage industry has begun to call it Poltross Burn Milecastle, which is how it is now signposted.

The Stanegate Roman road, which preceded Hadrian's Wall, crossed the Poltross Burn a few hundred yards to the south of Milecastle 48; part of its route can be seen descending a field to the river's edge.

The minor Stanegate fort of Throp stood on top of the ridge just to the southwest of Milecastle 48,[4] but it is not visible on the ground.

[1] Flanking the central space of the milecastle stood long barrack blocks, which are believed to have had more than one phase of construction.