The lower spiral, in this image, shows the end of panel fifty-one, and the beginning of panel fifty-two. At the end of panel fifty-one, the Dacians are building a fortification, in an elevated position. In panel fifty-two, the Romans prepare a fortification of their own, and Trajan receives a prisoner.
The upper spiral, in this image, shows panels fifty-seven and fifty-eight. In panel fifty-seven Trajan builds a large fortification, near a source of fresh water. In panel fifty-eight, Decebal appears before Trajan, to officially surrender.