When completed, it stretched for 73 1/2 miles from Bowness to Wallsend
[DOC] [TLE] Military Remains - Humanities Web [PAR] Its distance from the rampart varies from 18 ft. to 112 ft., but usually it does not ... 
from Bowness on the Solway to Wallsend on the Tyne, and is 73 1/2 miles in 
length.