This hall is longitudinally divided into a nave and two narrower side aisles separated by a symmetrical row of pillars, with a stupa in the apse. The stupa is surrounded by pillars and concentric walking space for circumambulation. Some of the caves have elaborate carved entrances, some with large windows over the door to admit light. There is often a colonnaded porch or verandah, with another space inside the doors running the width of the cave. The oldest worship halls at Ajanta were built in the 2nd to 1st century BCE, the newest ones in the late 5th century CE, and the architecture of both resembles the architecture of a Christian church, but without the crossing or chapel chevette. The Ajanta Caves follow the Cathedral-style architecture found in still older rock-cut cave carvings of ancient India, such as the Lomas Rishi Cave of the Ajivikas near Gaya in Bihar dated to the 3rd century BCE. These chaitya-griha are called worship or prayer halls. The four completed chaitya halls are caves 9 and 10 from the early period, and caves 19 and 26 from the later period of construction. All follow the typical form found elsewhere, with high ceilings and a central "nave" leading to the stupa, which is near the back, but allows walking behind it, as walking around stupas was (and remains) a common element of Buddhist worship (pradakshina). The later two have high ribbed roofs carved into the rock, which reflect timber forms, and the earlier two are thought to have used actual timber ribs and are now smooth, the original wood presumed to have perished. The two later halls have a rather unusual arrangement (also found in Cave 10 at Ellora) where the stupa is fronted by a large relief sculpture of the Buddha, standing in Cave 19 and seated in Cave 26. Cave 29 is a late and very incomplete chaitya hall. The form of columns in the work of the first period is very plain and un-embellished, with both chaitya halls using simple octagonal columns, which were later painted with images of the Buddha, people and monks in robes. In the second period columns were far more varied and inventive, often changing profile over their height, and with elaborate carved capitals, often spreading wide. Many columns are carved over all their surface with floral motifs and Mahayana deities, some fluted and others carved with decoration