The famous building known as Arthur’s O’on stood on rising ground above the north bank of the River Carron not far from the Carron ironworks. It was a Roman temple dedicated to the god Mars despite the latwer dark age connection with the mythical King Arthur. The building was shaped like a beehive or igloo and stood over twenty feet high with a similar base diameter. The four foot thick walls of dressed freestone narrowed towards the top which was open when detailed architectural drawings were prepared in 1726. From its position out in the open, well in front of the Antonine Wall, some have argued that it was a triumphal monument set up to further remind the Caledonians and other tribes of their defeat and subjugation to the might of Rome. By the sixteenth century it was recognised by scholars as a Roman monument of considerable importance but this did not save it from the Laird of Stenhouse who had it demolished to provide a cheap supply of dressed stones for a new weir. Pity – it would surely have been one of Scotland’s most important monuments if it had survived.
Ian Scott (2005)