Tullynally Castle is the ancestral home of the Packenham family. The oldest parts of the building date from the seventeenth century, its present appearance can be attributed to the second earl of Longford when the house was remodeled in the Gothic style by Francis Johnston, with later additions by James Shiel. The third earl added two wings and a tower in 1840 by Richard Morrison.

Inside the house the octagonal dining room is unusual, in the basement is a massive boiler used to heat the house, it is alleged to be the first use of central heating in the British Isles.

The gardens were laid out in the eighteenth century, drastic remodeling was carried out in the mid nineteenth century, including a artificial lake, a kitchen garden, and a grotto.