But magnificent as were the edifices in their garb of sandstone or granite or many-hued marble, the most extraordinary by far was that to which our guides ultimately led us. It was not the size of the structure that distinguished it, since the city boasted far larger buildings, and size in itself did not seem to have been an object with the builders; but the quality of the masonry and the style of the workmanship had surely no parallel in human experience. For the walls and the interior circles of columns were not of any material ever employed before, not of steel or of stone, of brick or of clay, or gold or of ebony; they were of a translucent yellow hue, the hue of amber, and seemed to be composed, if not actually of amber, at least of glass tinted amber color. This, however, was scarcely the most remarkable fact, for the floor was likewise translucent, and shone with an entrancing blue, the blue of sapphire; and sapphire seemed also the substance of the fretted and vaulted ceiling, from which hung images of great birds with wide-spread wings, giving a startling illusion of flight. Three successive circles of columns, each more massive than the last and all adorned at the base with bas-reliefs of strange fishes and stranger sea plants, supported the great arching expanse of the roof; and completely enclosed by the columns, on a steep and curving incline of the sapphire floor, were row after row of amber seats grouped in a half circle about a flat open space, and forming--so it seemed to me--a Grecian theatre of unique design. * * * * * As Rawson and I accompanied our guides into this queer building, we were so captivated by the architecture and so enthralled by the silence and the weird half-light of sapphire and amber that we did not at first observe that other human beings had preceded us into the place. It was long, indeed, before we could recover from the awed sense of entering some cathedral where all is reverential and unworldly; and it was long before, turning our eyes upon the theatre with its rows and rows of seats, we observed that not all the chairs were vacant as we had at first assumed. In the front tiers sat perhaps a hundred light-gowned individuals whose sedate and earnest faces proclaimed that they were convened for some solemn purpose.