St. Mochua, who is said to have died in 657, began the monastic community at Timahoe. The 96 foot high round tower is the only surviving evidence of any religious community that operated on the site. It dates back to the twelfth century, and is one of the largest in the country, as well as the biggest in diameter.
The Round Tower has a very attractive Romanesque doorway, situated far enough above the ground that the use of binoculars is necessary to view the intricate details of the carvings. Visible images include figures of heads with interwoven hair.
Sketchy historical writings refer to a church being built on the site in around 1056 and an extreme shortage of monks, with the original order dissolving. In the twelfth century, monks returned to the site.
After the suppression period, the land at Timahoe was given to Sir Thomas Loftus, then to the Cosby family who converted the church into a castle.