The circular region, limited on three sides by the river's course, is the historical field of Soria--part of the province of the same name, Numantia, Rome's great enemy and almost the cause of her ruin, lay somewhere in this part of the country, though where is not exactly known, as the great Scipio took care to destroy it so thoroughly that not even a stone remains to-day to indicate where the heroic fortress stood. In the present day, two cities and two cathedrals are seated on the banks of the Duero within this circle; the one is Soria, the other Osma. The latter was a Roman town, an early episcopal see, and later an Arab fortress; the former was founded by one of the Alfonsos toward the end of the eleventh century, as a frontier fortress against Aragon to the east, the Moors to the south, and Navarra to the north. The town grew apace, thanks to the remarkable _fueros_ granted to the citizens, who lived as in a republic of their own making--an almost unique case of self-government to be recorded in the middle ages. The principal parish church was raised to a suffragan of Osma in the twelfth century. Since then, there has been a continual spirit of rivalry between the two cities, for the former, more important as a town and as the capital of a province, could not bend its head to the ecclesiastical authority of a village like Osma. Throughout the middle ages the jealousy between the two was food for incessant strife. Pope Clement IV., at Alfonso VIII.'s instigation, raised the Collegiate at Soria to an episcopal see independent of Osma, but the hard-headed chapter of the last named city refused to acknowledge the Pope's order, and no bishop was elected or appointed. This bitter hatred between the two rivals was the origin of many an amusing incident. Upon one occasion the Bishop of Osma, visiting his suffragan church in Soria, had the house in which he was stopping for the night burnt about his ears. He moved off to another house, and on the second night this was also mysteriously set on fire. His lordship did not await the third night, afraid of what might happen, but bolted back to his episcopal palace at Osma.