Perhaps the rocky mound on which the church was built, standing south of Hadrian's Wall and the Vallum, was already the site of a Roman shrine. However, of this we have no evidence. Maybe the Saxon settlers who chose the spot for their village just liked the view as we do today.
Milecastle 12 of Hadrian's Wall has never been definitively located although its measured location along the line of the Wall was considered to be within the enclosure west of Towne Gate. This was originally the site of Town Farm, later Tulip's Haulage Yard, and recently of the newly built development of houses known as Tulip Mews.
Archaeological investigation of the Town Farm site during this development failed to locate remains of the Milecastle once the farm buildings had been demolished although did reveal limited remains of the curtain Wall itself.
- MacLauchlan (1858) failed to mark the milecastle on his survey, suggesting that he could not see it.
- Cadwallader Bates in his history of Heddon on the Wall (1886) states in footnote 3: "This milecastle probably stood to the east of the pond, on the hill-top now covered with ruins of cottages. The Rev. G. Bowlker, vicar of Heddon, has heard that the people who lived in these cottages, in digging a hole in front of them for burying a horse, came on old foundations and what they described as a grave-stone with letters on it. This they promptly broke up. Can it have been an inscription recording the names of Hadrian and his legate Platorius Nepos, like those found in the mile-castles at Castle-Nick, Milking Gap, &c?"
- In 1926, J. A. Bean (County Engineer to Northumberland County Council) said, ‘The road contractor had noted a large stone with a pivot hole therein at a point on the north side of Heddon Town Farm enclosure, on the south side of the main road, during the road widening in 1926’.
- This discovery of what sounds like a pivot stone from the north gate of a milecastle was recorded in Archaeologia Aeliana in the following year: ‘The gateway of this milecastle was found in making alterations to the road in 1926, close to the west end of an out-building of Town Farm.’ (Brewis 1927, 121, n.19).
- Recent archaeological investigation for the development of new houses at Tulip Mews, after demolition of the old farm buildings of Town Farm, located the remains of Hadrian's Wall but revealed no sign of the milecastle.
Mushroom Row consisted of two rows of houses situated just north of the modern library, south of Chare Bank, which is a footpath which partly follows the ditch of the Vallum. After demolition of the houses in 1955 the site was used by the Amos Brother's Roman Wall Forge and is now the location of a large private house, Forge House.
However, as Bates mentions a "hill-top now covered with the ruins of cottages", this, and its location south of the Vallum, seem to make Mushroom Row an unlikley candidate.
The cottages he refers to are more likely to have been located in the enclosure that is now occupied by Tank House due west of the enclosure that held the buildings of Town Farm and the track which runs from the old road south towards Garden House.
Tank House is located on the north side of Chare Bank. The house name refers to the stone-built water tank that stood on this hilltop site. It was the village water supply from the mid C19th, fed from springs rising near East Heddon. It went out of use when a metal tank on legs was provided further south, close to the library.
Graeme Stobbs (Society of Antiquaries of Newcastle upon Tyne) came to the same conclusion in a short note published in 2019 from which the following figure has been taken:
The reason why Milecastle 12 was not located at the Town House farmyard in 1928 or in 2019, is that it actually sits some distance to the west, within the enclosure now known as Tank House Field (No. 1 on map). It might be objected that the eastern (Town Farm farmyard) possibility is one Roman mile from Milecastle 13, but it is well known that milecastles and turrets often lie slightly away from their measured positions for topographic reasons, and the higher ground of the Tank House enclosure may well have been preferred to the measured position. The site of the next milecastle to the east (11) is not established; measurement from its assumed position would place Milecastle 12 just to the west of the Town Farm site.
Archaeological evaluation work within Tank House Field has been quite limited and there is probable potential that remains of Milecastle 12 may well survive within the enclosure, probably to the north-west of the current dwelling house. This should be considered more likely to be the milecastle site than the Town Farm location.
The track on the left also cuts through bed-rock, runs up towards the rear of Garden House, and divides the enclosures of the original Town Farm and Tank House.
This location is close to the suspected site of Milecastle 12, although it has never been found. Recent archaeology has shown it wasn't in its measured position under the buildings of Town Farm (later Tulip's Haulage Yard) slightly further east.
The road was widened in 1926. At the same time, or perhaps earlier, it was cut deep into sandstone bedrock (visible below the wall) to remove an unnecessary hill. As the milecastle wasn't revealed on the line of Hadrian's Wall further east there is a high possibility that it is located somewhere on the hill in the garden above the wall, the back garden of Tank House. There were old buildings here above the road, indicated on old plans, and it might of course have been completely destroyed.