Close to the Sat Mehal is a circular building, which, so far as is at present known, is unique. It may almost be described as a hollow dagoba, being a circular enclosure surrounded by a wall, but empty in the centre, at least containing nothing now. Originally, it may have had a shrine in its centre, or tabernacle of some sort, containing a relic or, more probably, a sacred Tree. It is surrounded by a procession-path, enclosed by a highly-ornamental screen, and beyond this by a second gallery adorned with a range of slender pillars, like those which surround the dagobas at Anuradhapura (Woodcut No. 107); below this, again, is a richly-carved stylobate. Four flights of steps lead up to its procession-paths, more magnificent and elaborate than any others that have yet been discovered in Ceylon. They all have most elaborate moon stones to start from. Their risers are each adorned with twelve figures of dwarfs, and their side-pieces, or jambs, are also of exceptional richness, and each has a pair of Naga-headed dwarpals on each side of its upper flight. The photographs are sufficient to show that this is one of the most interesting buildings in Ceylon, as well as one of the richest in sculptural decorations; but unless the antiquities of Java throw some light on the subject, we must be content with ignorant admiration till some one capable of investigating its history visits the place.[247] Besides these, there are in Pollonarua several of those groups of pillars, without roofs or walls, which we tried to describe in speaking of Anuradhapura. One, called the Audience Hall, seems to be very similar to those of the northern capital; another, known as the Hetti Vihara, is more extensive, and may really be the foundation of a vihara; but till we have plans and more details it is needless speculating on what they may or may not have been. Although built in brick, and very much ruined, there still exist in Pollonarua a palace and a vihara--the Abhayagiri--which was really a residence, and whose examination would, no doubt, throw considerable light on the arrangement of similar buildings in India. That information might, however, be difficult to obtain, and, till the simpler and more monumental buildings are examined and drawn, its investigation may well be postponed.