Though little remains of the original structure today, the site offers a glimpse into the medieval landscape of Mayo, when such fortifications dotted the countryside. The castle likely dates from the 15th or 16th century, built during a period when local Gaelic lords and Anglo-Norman families vied for control of the region’s fertile lands and strategic routes.

Archaeological evidence suggests the castle was a tower house, a type of fortified residence common throughout Ireland during the late medieval period. These structures typically consisted of a rectangular stone tower, three to five storeys high, with thick walls designed to withstand attack. The ground floor would have been used for storage, whilst the upper levels contained living quarters for the lord’s family, complete with fireplaces, narrow windows, and perhaps even a small chapel. The castle at An Tearmann would have commanded views across the surrounding countryside, allowing its inhabitants to monitor movement along nearby roads and waterways.

Local tradition connects the site to various historical events, though separating fact from folklore proves challenging. What is certain is that by the 17th century, like many Irish castles, this stronghold had fallen into disuse; changing military technology and political upheavals had rendered such fortifications obsolete. Today, visitors to the site can trace the outline of the castle’s foundations and imagine the bustling household that once occupied this now peaceful spot, where cattle graze amongst the stones that once formed part of Mayo’s defensive network.