The centrepiece of this fascinating historic site where St Tola founded a monastery in the 8th century is the four-storey, 15th-century O'Dea Castle. Today it houses the Clare Archaeology Centre, which has a rooftop castle walk and a museum displaying local artefacts. You'll also find a tearoom and a bookshop. A 5km history trail around the castle passes some two-dozen ancient monuments, from ring forts and high crosses to a prehistoric cooking site. Dysert O'Dea is just off the R476, 5km south of Corofin.
The site's church dates from the 12th century, as does the high cross, the White Cross of St Tola, depicting Daniel in the lion's den on one side and a crucified Christ above a bishop carved in relief on the other. Look for carvings of animal and human heads in a semicircle on the southern doorway of the Romanesque church. There are also the 5m-high remains of a round tower.
In 1318 the O'Briens, who were kings of Thomond, and the Norman de Clares of Bunratty fought a pitched battle nearby, which the O'Briens won, thus postponing the Anglo-Norman conquest of Clare for some two centuries.