Cave 9, Ajanta
Cave 9, an early chaitya hall, dates to the 1st century BC. Its entrance facade, like most of the chaityas, includes a large chaitya arch framing a window with imitation timber construction. The large window was usually the first feature to be cut into the rock of a chaitya. It served two purposes: it allowed light into the cave, and it permitted rock to be easily removed from the cave during the process of excavation.
Excavation then proceeded from the top down, a painstaking process which at least had the benefit of not requiring scaffolding during construction.