In its original form, the arch is shaped like the cross-section of a barrel vault. It is called a chaitya arch when used on the facade of a chaitya hall, around the single large window. In later forms it develops well beyond this type, and becomes a very flexible unit, "the most common motif of Hindu temple architecture".
The arch takes its shape from the cross-section of a barrel vault in its initial design. When employed as part of a chaitya hall's facade, around a single large window, it is known as a chaitya arch. Over time, this type of arch has become incredibly adaptable and widespread, serving as the most common architectural feature in Hindu temples.