The real architectural event on the island is the country house nearby, a building that wears its history in layers: an eighteenth-century core, a substantial early-1820s remodelling, a billiard room added in 1856, and a long gallery tacked on around 1900. The result is a house that grew by accretion rather than grand plan, yet holds together with some coherence.

The most significant intervention came in the early 1820s, when the architects Richard and William Morrison took an existing house and transformed it into something considerably more ambitious. The Morrisons added a single-storey Doric portico to the southern entrance front, projecting two-storey wings that pull the plan into an H-shape, and a two-storey service range. The central block runs to three storeys and seven bays, with a hipped roof and a Wyatt window, that distinctive late-Georgian type with a broad central light flanked by narrower ones, positioned above the portico on the first floor. The rubble-stone walls were originally rendered, and blue-grey quoins mark the corners with deliberate emphasis. Inside, the entrance hall stretches into a long gallery divided by paired scagliola columns, a material made from gypsum and pigment to imitate marble, topped with Ionic capitals. Fine plasterwork survives throughout much of the interior. The Morrisons also designed the classical entrance gateways, and the formal gardens, which include a significant arboretum, spread across the whole island demesne.

The house passed into the ownership of University College Cork, and in the 1970s the interior was restored by Richard Wood to accommodate a collection of Irish paintings. That arrangement proved fragile: a leaking roof eventually forced the removal of the paintings. The arboretum and gardens continue to draw visitors to Fota Island, though the house itself tells a more complicated story, one of careful restoration undone by the ordinary persistence of rain.