The walls of the Octagon had marble revetments. From these, mortars from the substrate (with or without traces of marble slabs), nails to secure the slabs, slab fragments, and a limited number of intact slabs survive. Specifically, marble slabs are preserved at the base of walls, while the substrate mortar and nails are preserved to a height of 5.00 meters above the floor, which leads to the conclusion that the walls were covered in marble up to the genesis of the arches belonging to the niches. A great deal was learned from the study of the surviving remains about the techniques for setting marble slabs, substrate mortars, and forms of revetment.
The representation of the revetment’s original form is based on the detailed recording of surviving nails and corresponding holes, the marble slabs preserved along the bases of walls, and the imprints left in the substrate mortar by slabs now missing. In accordance with the architectural drawing, the wall revetment was done using successive horizontal zones of marble slabs, inside which panels were created.
The Octagon’s wall revetment, according to the form which resulted from the reconstruction drawing, belongs according to P. Asimakopoulou-Atzaka to that group of monuments in which the wall decoration, organized on the basis of an overall architectural design, also contained opus sectile in added or inlaid σε παραθετική ή ενθετική form.
The evidence surviving in situ, and above all the absence of marble slabs in the upper zones, does not allow us to draw any conclusions concerning the type of marbles used, nor about the design of the opus sectile with which the panels were varied. However, the significant number of crustae found in the excavation of the monument recalls representations containing geometric and floral motifs.
