Arthur's Oven or O'on was a Roman temple which until 1743 stood on rising ground above the north bank of the River Carron not far from the old Carron ironworks in Stenhousemuir, near Falkirk, Scotland1.
See: http://canmore.rcahms.gov.uk/en/site/46950/details/arthur+s+o+on+stenhouse/ and https://romansinscotland.com/arthurs-oven-roman-temple/