The estate is most closely associated with the Burke family, later the Earls of Clanricarde, who were among the most powerful Hiberno-Norman dynasties in the west of Ireland. The great castle they built here in the early seventeenth century is the more celebrated structure on the grounds, but the later country house represents a quieter layer of the site's long occupation, one that tends to be passed over in favour of its more dramatic neighbour.

Without more detailed notes to draw on, the precise construction date and full architectural history of the house remain difficult to set out with confidence. What is clear is that Portumna Demesne as a whole developed over several centuries, with the landscape around the castle shaped and reshaped to reflect the tastes and ambitions of successive occupants. The formal walled gardens, which survive in part, give some sense of how the grounds were once managed as an ordered, productive estate. The deer park and woodland walks that extend toward the lough were characteristic features of such demesnes, designed as much for the display of land and status as for practical use.