THE MAUSOLEUM
89
Though an octagon externally, internally it is circular, with four semicircular and four square niches or chapels. The diameter of the circle is only 43 feet 3 inches. The main feature of the decoration is the eight great Corinthian columns standing out from the wall, monoliths of Egyptian granite carrying a very heavy entablature, highly ornamented, on which in turn rest eight shorter —too short—columns of alternate granite and porphyry, again carrying a smaller entablature which reaches to the spring of the cupola. All this elaborate arrangement of column and entablature is purely decorative, not structural, and might be removed without affecting the stability of the building. The cupola is of brick and shows a tan-shaped construction of superimposed, relieving arches, each one springing from the crowns of the arches below it, a construction said to be unique ln Roman building and presenting a very pleasing scheme of decoration, like the scales of a fish, when seen from inside. Below the cornice of the upper row columns runs a frieze representing scenes of the chase, and round medallions with human heads. **■ 'las been conjectured that two of these heads in the fourth section on the left-hand side may be 110‘traits of Diocletian, and Prisca, his wife.