The artifact would have been painted on the Antonine Wall.
71 Photos taken at the Hunterian Musuem at the University of Glasgow on June 9, 2019.
C. 142-180 AD
Inscription Reads: " IMP C T AE HADRIANO ANTONINO AVG PIO P P VEX LEG XX VV FEC PP IIII CDXI "
Translation: " For the Emperor Caesar Titus Aelius Hadrianus Antoninus Augustus Pius, Father of his Country, a detachment of the Twentieth Valiant and Victorious Legion Built [this] Over a Distance of 4411 Feet "
Sandstone Distance Slab, Object Number GLAHM:F.15
More Information at:
http://collections.gla.ac.uk/#view=list&id=218b&what=Distance%20Slab&locality=Antonine%20Wall
Check out the research from Dr. Louisa Campbell: https://twitter.com/PPIP_Paints