How did Robert Adam use a triumphal arch design at Kedleston Hall?

At Kedleston Hall, Robert Adam utilized the triumphal arch design as an exterior expression of the building's domed interior hall.1

This application on the south front of the estate represents the first instance of this specific Roman architectural form being employed in domestic architecture. By incorporating this motif, Adam successfully translated a monumental, public-facing classical structure into a private residential context, reflecting his innovative approach to Neoclassical design.1