Arthur's O'on () was a stone building thought to be Roman temple that, 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, Scotland. The structure is thought to be the 'stone house' which gave its name to Stenhousemuir. Early historians discussed historical and mythical associations with the site and by 1200 the estate of Stenhouse on which it stood had been named after it.
Construction myths
One manuscript of the Historia Brittonum by Nennius refers to Arthur's O'on as a "round house of polished stone" by the River Carron, attributing it to Carausius, in a passage primarily referring to Septimius Severus. John of Fordun in the 14th century recorded in his Chronica Gentis Scotorum that the structure was built by Julius Caesar to mark the northern limit of the Roman Empire, and another more fanciful belief that was once popular was that Caesar used it as a secure quarters in which he slept, the building being dismantled stone by stone to be re-assembled at the emperor's next stop for the night. George Buchanan in the 16th century saw it as a memorial to some great Roman victory over the Scots. In this tradition, the building commemorated a victory of the Roman emperor Vespasian at Camelon and his capture of the jewelled crown and regalia of the Pictish kings.
Names
In a Charter to Newbattle Abbey (Midlothian) in 1293 a reference is made to furnus Arthur (Latin for "Arthur's Oven"), indicating that it was a well established feature and of unknown origin even at that relatively early date.
Henry Sinclair, Dean of Glasgow about 1560, calls it Arthur's Huif; and Alexander Gordon speaks of it as Arthur's Hoff. Julius's Hoff is also recorded. Hoff and Huif (cf. Old English hof: "house", "hall") are Scots for a house or hall.
Setting
A road to Alloa and Airth passed by the back of the Forge Row and through the Stenhouse estate; Arthur's O'on stood on the north-east side of this road. Early historians often discuss it along with the Roman fort at Camelon.
The building was on the declivity of rising ground, supported by a basement of stones, projecting out from below the lowest course of the building; it was so far from being upon a level area, that a great part of the basement, and four courses of the stones on the south side, were hidden in the earth. The marks of three or four steps, which may have formerly led from the ground to the entrance of the building, were visible at one time.
The traces of a broad ditch could be seen at one time on the northern side; suggesting that a regular vallum (rampart) and fosse (ditch) had once surrounded the building.
Description
The O'on was built of dressed freestones which were not mortised into each other and no mortar was used. Each stone had a lewis hole in it to allow secure lifting with a hinged pair of metal callipers. In appearance the O'on was shaped like a beehive, being circular on plan with a domed roof. The perpendicular height, from the bottom to the top of the aperture, was ; the external circumference at the base, ; internal circumference, ; external diameter at the base, ; internal diameter, ; circumference of the aperture, ; diameter of the aperture, ; height of the door from its basis to the top of the arch ; breadth of the East facing door at the base, ; height, from the ground to the top of the key-stone of the door, ; breadth of the wall at the base, measuring at the door, ; thickness of the wall where the arch springs, ; and height of the basement on which the building stands, . The door is said to have had an iron gate, the removal of which by the Monteiths of Cars brought a curse upon the family.
Round the interior of the building there were two string courses at distances of respectively above the paved stone floor, and in several places, notably over the door, there may have been much weathered carvings in which eagles and the goddess Victory are said to have been represented. A huge stone stood in the interior, possibly an altar or the base of a bronze statue. The O'on may date to the period of occupation of the Antonine Wall.