It is not clear when the castle was first built. It might date back as far as 1430. The roof dates from the 17th century. 
After the building was made bigger and improved, it was used as the house for the Under Secretary of Ireland from 1782. In 1922, it became the house for the first United States ambassador to Ireland. After the ambassador moved to the Chief Secretary's Lodge, the Papal nuncio used the building until 1978 when he moved.
In 1978, the building was in bad shape. It could not be repaired. When they started to break down the building, they found the towerhouse inside the bigger building. It was restored to its old form.