So our next order of business was to see the site of and last remaining tower of the 12th century Kildare Castle. Located just down the road from the market square, in behind the Silken Thomas premises we found the remains of one of the most important Castles of the Normans in Leinster, home to the Fitzgerald family. It is most likely that Strongbow built a motte and bailey castle in Kildare when it was his headquarters. The first mention of a castle in Kildare dates back to approx 1185. It is unlikely that a stone castle would have been erected by 1185: if it were, it would have been among the earliest in Ireland.
The most direct evidence we have for the date of the building of a castle in Kildare comes from the record of an Inquisition held in 1302. The Inquisition held that: William formerly Earl Marshal, senior, built originally the castle of Kildare on the soil of the church of Kildare, without the consent of the Bishop and Chapter thereof. It would appear therefore, that the castle was built, or at least commenced, before 1219 when William, the earl Marshal senior, died.
The castle passed in time to the deVescy family in 1290. Edward Bruce, brother of King Robert Bruce of Scotland, besieged the castle in the winter of 1315/16 for three days before being driven off. In 1316 the king elevated John Fitzthomas [Fitzgerald] to the newly created title of earl of Kildare in recognition of his services during the Bruce invasion and granted him the castle of Kildare. So began the Fitzgerald association with Kildare castle and town. Today one tower (4 towers were mentioned in 1331) and parts of the castle bailey wall remain. The tower was originally a 13th. Century gatehouse and it was converted to a residential tower, possibly in the late 15th. Century. The tower retains openings related to both periods. It was occupied as a dwelling house until lately. The bailey wall bounds the park on the E. N. and W. sides. There are 2 bastions incorporated in the wall. The walls are probably 16th or 17th century on 13th century foundations. The bailey was also the site of Lord Edward Fitzgerald’s home in 1798. This building has completely disappeared, probably being demolished as a reprisal after the 1798 Rebellion. The tower is best seen from the car park of the Silken Thomas Restaurant while the castle bailey is now largely occupied by a Co. Council yard, which may be approached from the lane on the left side of the Silken Thomas Restaurant.