Ambitus Altaris an expression sometimes used for the enclosure which surrounded the altar. It was probably distinct from the presbyterium, or chorus cantorum (i.e. an enclosed space in front of the altar reserved for the use of the inferior clergy), and there was usually between the presbyterium and the altar a raised space. called solea. Probably no early example of an ambitus altaris now exists. In St. John Lateran many fragments of marble slabs, with the plaited and knotted ornament characteristic of this period, are preserved in the cloister, and may probably be fragments of the ambitus mentioned above. The expression ambitus altaris may perhaps sometimes stand for the apse, as surrounding the altar.