The origins of the Aylmer family in Ireland are unclear, but they were certainly here before the end of the 14th century and by the mid-1400s were living at Lyons, County Kildare (the estate was sold by the hopelessly-indebted Michael Aylmer in 1796 to Nicholas Lawless, first Lord Cloncurry). In 1559 Gerald Aylmer, then aged 11, inherited an estate elsewhere in the county, at Donadea, which had been bought by his father the previous year and where there may well have been some kind of castle, possibly erected by the de Berminghams who had previously held the property. It is thought that in due course Gerald Aylmer constructed a new tower house for himself. This work may have been undertaken around 1587 when he married Mary Travers, widow of the attainted third Viscount Baltinglass. The tower is now the oldest part of the present Doneadea Castle. A lawyer by profession, Gerald Aylmer initially spent much time at the English court but adherence to the Roman Catholic faith might have hindered his chances of preferment. Nevertheless, he was knighted in 1598 and then created a baronet in 1622. Two years later, he and his (second) wife were responsible for building a three-storey block adjacent to the tower. The Donadea estate was duly inherited by the couple’s only son, Sir Andrew Aylmer who, although not a participant in the Confederate Wars from 1641 onwards, was imprisoned in Dublin Castle. Meanwhile, the house his father built was burnt and the lands confiscated; they were returned to the family in 1662. Another assault and fire struck the property during the Williamite Wars. Still staunchly Catholic, a succession of Aylmers then all died young, often leaving infant heirs until the time of the sixth baronet Sir FitzGerald Aylmer, who although barely a few months old when he inherited the estate in 1737, managed to live for another 57 years. Raised in England as a member of the Established Church, it was Sir FitzGerald who undertook an extensive reconstruction of the old family house, an old plaque explaining that this work had begun in 1773. 

As mentioned, Donadea Castle assumed much of its present form in the last quarter of the 18th century, thanks to Sir FitzGerald Aylmer who inserted large window openings with granite sills into the old building, as well as the canted first-floor Venetian window on the south side of the building. Donadea Castle is U-shaped, a recessed central section flanked by two three-storey towers, one of which was the original residence built by the first baronet. Between the towers is a single-storey bowed entrance screen, probably early 19th century and tentatively attributed (by Andrew Tierney) to Sir Richard Morrison. It may be the latter was also responsible for the rest of the Tudor-style decorations on the building, such as the lines of battlements along the roofs and mouldings above the windows. All of this would have been commissioned by the seventh baronet, Sir Fenton Aylmer, founder of the Kildare Hunt. Morrison could also have been the architect of a free-standing crenellated tower to the west of the building; above a staircase window is a datestone of 1837 with the motto Non Dormit qui Custodit (He who guards does not sleep) proposing that the tower was used as a muniments store. This tower was commissioned by the eighth baronet, Sir Gerald Aylmer, who was also responsible for many other improvements on the estate, not least the creation of an eight-acre enclosed garden immediately behind the castle, as well as the demesne wall, gate lodges and the planting of a fine lime avenue. 

The ninth Aylmer baronet, Sir Gerald, inherited the Donadea estate in 1878, but died five years later, followed in 1885 by his heir, Sir Justin Aylmer: aged just 21 and an undergraduate at Cambridge, he was killed in a cycling accident. While the baronetcy then went sideways (to a younger son of the seventh baronet and then, just two months later, to his grandson), Donadea was inherited by Sir Justin’s only surviving sister, Caroline Aylmer, who lived there unmarried for the next half-century. On her own death in 1935, she left the property to the Church of Ireland, which quickly sold on the estate to the Land Commission. In due course, the castle was unroofed and the surrounding lands handed over to Coillte, the state-owned forestry body. Alas, while Coillte may be first-rate at looking after trees, its record in taking care of any buildings is pretty dismal, as can be seen by visitors to Donadea who over successive years have seen the castle and its surroundings allowed to fall further and further into dereliction, to the point that now cracks are appearing in walls and collapse is a real possibility. Given the property’s history, its convenient location and popularity as a site, this neglect seems especially reprehensible. Indifference can be the only explanation for Coillte’s failure to ensure Donadea Castle remains in decent repair; why, for example, have surviving features such as the charming Gothic-style wooden frames in many windows, not been removed and preserved? Why is it that a rare example of 17th century bay window with stone mullions should now be crudely filled with cement blocks (while the stonework above is left to become dangerously loose)? Unless serious intervention occurs soon, little of consequence will be left here. Another blot on our record of caring for the country’s architectural heritage.