Actually, this was a triangular enclosure (peribolos) of polygonal masonry, surviving in a rather good condition. The east wall is intact; there survives a large section of the west wall, while the south wall has been obliterated. We have represented a simple enclosure, with its floor 1m above the level of the road, as it incorporated the 7th cent. BC altar. The speculative representation does not comprise the even more tentative propylon which is thought to have defined the monument’s east side. This monument remains in its place until the Roman period and any changes are limited to the significant rise of the ground level in the surrounding area [Lalonde, G.V., ‘A Fifth Century Hieron Southwest of the Athenian Agora’, Hesperia 37 (1968), pp. 123-133, plates 35-37].