[RecycledEle]

> The thing is only one and a half foot tall on average

Stone walls tend to be taller when built, and then decay over thousands of years.

[Retric]

Many stone walls ~1/5th this age are still roughly intact. Surprisingly long sections of Hadrian’s wall would still be useful defensive fortifications.

This is a field of rubble but you can roughly figure height from the stones that remain.