Wall Mile 17 [HB 173–4]
Soon after the Robin Hood, we slip back down into the ditch via some handily located steps in what looks like (but isn’t) part of somebody’s garden. We are back on the line of the northern lip of the ditch, although along here it has been greatly degraded over the years to the point where it is barely noticeable in places. The Wall climbs very gently to a crest, just before which it changes course onto a new alignment, almost due east (since Milecastle 20 we have been on a slightly more southerly line). The fact that this realignment happens before we reach the crest has led one researcher to suggest that you can tell the way the Wall was laid out (but not necessarily built: they were two different processes) by the convenient fact that roads and mural barriers tended to use the far side of a hill and not the top to sight their lines. Hence, if this supposition is correct, this section was being laid out from east to west. Interestingly, the Vallum, which has been running parallel with us for some way, ignores this turn and ploughs straight on across the countryside, flattened now but still visible from the air as a crop or soil mark.
After that turn, and some 200m down the gentle slope towards the by-now-very-obvious Whittledene reservoirs, we reach a point opposite the location of Milecastle 17 (Welton).
Milecastle 17 (Welton) [HB 173; haiku]
This was a short-axis milecastle, excavated in 1931 and 1999, its northern part lying beneath the modern road.