The Hill of Allen, is a volcanic hill surrounded by the Bog of Allen, and lies just 7 km north-west of Newbridge, and rises to a height of approximately 676 ft. The Hill of Allen is reputed to have once been the site of a camp / royal residence occupied by Fionn MacCumhaill and the Fianna, who hunted in its forests and organised chariot races at its foot.

It is said that Fionn used the surrounding flatlands as training grounds for his warriors. There are what are said to be faint traces to indicate the site of an old fort on top of the hill, and there are indications that the current levelled top of the hill was formerly surrounded by earthen embankments. A small mound called Suidh-Fionn, (Fionn’s Chair), occupies the highest point, and it is there that Aylmer built the Tower.

However over recent years extensive quarrying has noticeably changed the profile of the hill.

Directory of archaeological sources relating to County Kildare (02E1097) indicates that a cist site / burial chamber, and a tumulus site / burial ground are located in close proximity to the Tower on the top of the Hill of Allen.

Sir Gerald George Aylmer completed the construction of the tower – known as “Aylmer’s Folly,” circa 1861. Brothers Lawrence and William Gorry were the masons and their names are cut on the landing at the top of the stairs. The Tower rises to approximately 60 feet from the base, and has an internal diameter of approximately 9 feet. Built of limestone, the tower has an internal staircase leading to the top; the names of those involved in constructing the tower are engraved on these staircase steps. On the outside of the tower there are numerous inscriptions, and Eileen Ryan in a Leinster Leader article notes that on the flagstones the visit of the then Prince of Wales (Edward VII) is recorded: “September 16 A.D. 1861 H.R.H. The Prince of Wales ascended this Tower.”

Eileen Ryan in a Leinster Leader article in 1963 notes that when digging the foundations the workmen discovered a cave, nine feet deep, filled with soft clay at the bottom of which they came upon a remarkably large human skeleton, which was believed in the neighbourhood to have been that of the giant Fionn Mac Cumhail. The tower has been closed for many years, although it is said that the views of Kildare and surrounding counties are spectacular from the top of the tower.

In all excluding the names of Aylmer and the Gorry brothers, there are 82 names carved on the steps of the tower, 77 males and 5 females, all from the following townlands: