According by what was passed on by Janus' Order, mysterious unintentional materializations have been happening within the boundaries of Rome since 2nd century C.E., with a whole squad of the praetorian guard tasked with handling the phenomenon. Unfortunately, the troubled history of Janus' Order from the fall of the Western Roman Empire onward, which caused the loss of countless documents, made it impossible to gather accurate information on the origins of SCP-140-IT for a long time.
Another important data source about SCP-140-IT is a record compiled and updated over the centuries by the Confraternity of Saint George's Knights: the Georgites took care of studying and concealing the anomaly for the whole period of papal Rome, without ever reaching an unanimous agreement on whether it was "divine" or "hellish".
Following the annexation of the Papal States to the newly founded Kingdom of Italy, SCP-140-IT was one of the first paranormal phenomena studied by the Royal Institute of Italian Anomalies. The cooperation between the Institute and the Order, but above all the access to part of the Confraternity's archives after the Lateran Treaty, made it possible to collect the most complete set of information about SCP-140-IT, inherited and expanded by the Foundation's Italian branch after World War II.
By studying the history of the phenomenon, it was also learnt how the perimeter bordering the materialization area gradually changed, adapting to the conventions on the boundaries of Rome from time to time. Indeed, the current overlap with the A90 highway began after that road was built in 1951.
The mystery of the origin of SCP-140-IT was solved for good in June 2010, when Janus' Order went on an expedition to Istanbul financed by the Italian and Turkish (TR) branches and discovered an archive of the Order's ancient Byzantian branch. Among the texts was the lost De Operĭbus Arcanis (“About the Secret Works”), containing passages describing SCP-140-IT. A translation is attached below.
Marcus Turpilius Domitius, De Operĭbus Arcanis, Liber III, 6
[…] Trajan, optimus princeps, was thus succeeded by Hadrian, who was certainly not inferior to him in terms of intellect, virtue and generosity. What Trajan conquered, expanding the boundaries of the Empire like no one before, Hadrian was able to keep, giving prosperity to both the citizens and the provinces. He was a great art amateur, and perhaps he was especially knowledgeable in architecture. The temple in Rome, ruin of Apollodorus, is his. The tomb where he is now resting with his bride is his. The Pantheon risen from the ashes and the mighty wall on the borders of Caledonia are his.
But alas, even the best among emperors may fall into error, although they want nothing but peace for their people. Having to rule the greatest of all empires, greater than Alexander's, and having personally visited all of it, the pater patriae yearned for a way to make travels easier in such a vast territory. Therefore, he summoned sages from everywhere, masters of the arcane arts, asking them to craft a hex, so that goods and wagons and legions would be able to travel countless miles in the blink of an eye, as if they were walking in Mercury's sandals. He also asked that Rome, the capital city of the world, was placed where it deserved to be: at the exact center of the canvas.
Years passed, and just when the emperor had lost all hope, the sages returned with their response. They were sure that they could meet his demand. However, a sad surprise awaited them, once the consular roads were paved, once the milestones were carved and the formulas were uttered. Perhaps it was due to the difficulty in realizing such a prodigy, or maybe a punishment from the gods for daring so much, but the hex span out of their control, as it still spins out of ours. The Order's initiates know this well.
And yet, the adage repeated in every corner of the Empire since time immemorial was never so true: OMNES VIAE ROMAM DUCUNT.