become an elaborate frame, spreading rather wide, around a circular or semi-circular medallion, which may contain a sculpture of a figure or head. An earlier stage is shown here in the entrance to Cave 19 at the Ajanta Caves (c. 475–500), where four horizontal zones of the decoration use repeated "chaitya arch" motifs on an otherwise plain band (two on the projecting porch, and two above). There is a head inside each arch. Development of the chaitya Early Chaitya halls are known from the 3rd century BCE. They generally followed an apsidal plan, and were either rock-cut or freestanding. Rock-cut chaitya halls The earliest surviving spaces comparable to the chaitya hall date to the 3rd century BCE. These are the rock-cut Barabar Caves (Lomas Rishi Cave and Sudama Cave), excavated during the reign of Ashoka by or for the Ajivikas, a non-Buddhist religious and philosophical group of the period. According to many scholars, these became "the prototype for the Buddhist caves of the western Deccan", particularly the chaitya halls excavated between the 2nd century BCE and 2nd century CE. Early chaityas enshrined a stupa with space for congregational worship by the monks. This reflected one of the early differences between early Buddhism and Hinduism, with Buddhism favoring congregational worship in contrast to Hinduism's individual approach. Early chaitya grhas were cut into living rock as caves. These served as a symbol and sites of a sangha congregational life (uposatha). The earliest rock-cut chaityas, similar to free-standing ones, consisted of an inner circular chamber with pillars to create a circular path around the stupa and an outer rectangular hall for the congregation of the devotees. Over the course of time, the wall separating the stupa from the hall was removed to create an apsidal hall with a colonnade around the nave and the stupa. The chaitya at Bhaja Caves is perhaps the earliest surviving chaitya hall, constructed in the second century BCE. It consists of an apsidal hall with a stupa. The columns slope inwards in the imitation of wooden columns that would have been structurally necessary to keep a roof up. The ceiling is barrel vaulted with ancient wooden ribs set into them. The walls are polished in the Mauryan style. It was faced by a substantial wooden facade, now entirely lost. A large horseshoe-shaped window, the chaitya-window, was set above the arched doorway and the whole portico-area was carved to