No less than fifty-seven castles, monasteries, abbeys and fortresses are attributed to the Macnamaras, most notably Bunratty Castle, today home to an Irish theme park, Knappogue Castle, which was the ancestral home and which was occupied for ten years by Cromwell's forces, and Quin Abbey, founded for the Franciscan Order in 1402 by Siodha Macnamara.
This junior branch of the wide-spreading clan became prominent during the middle of the XVI century, when its principal member, Sioda MacConmara, having been elected chief of Clann-Cuilein, entered into negotiations with the government of Henry VIII, for the surrender of his territory to the Crown of England.

This family name is closely connected with Co. Clare and is the most important sept of Dál gCais - ancient Irish chieftains dating back to prehistoric times - after the O'Briens of this county. The name comes from Mac Conmara, meaning son of the hound of the sea, Co. Clare being on the Atlantic coast. Several castles have connections with the MacNamaras, including Bunratty Castle, near Shannon airport. The MacNamaras owned Bunratty Castle before it passed to the O'Briens. Knappogue Castle, nearby, was built by a MacNamara in 1487. Also in this part of Co. Clare is Cratloe Castle, built by the MacNamaras in 1610. The most important site in Co. Clare associated with the MacNamaras is Quin Abbey, six miles east of Ennis. The abbey was founded by Sioda MacNamara in 1402 and contains tombs of the MacNamara family.

QUIN ABBEY was founded by the MacNamaras around 1350.   Using the solid south curtain-wall of the old castle, they built a church from east to west.  North of the church they erected a residence for the clergy and a small sacristy. Sioda Cam MacNamara built the cloisters in 1402.  The bell-tower and Lady Chapel were erected by Mahon MacNamara in 1430.  Three years later he sponsored the Franciscan friars and allowed them to establish their friary in Quin.  The abbey was officially suppressed in 1541 and became O'Brien property in 1547.  The O'Briens, however, allowed the friars to continue living there.  By 1548 it had fallen into disrepair and was described as "one great church, now ruinous, covered with slate, and a steeple greatly decayed". 

The MacConmara were one of the most influential clans of Thomond and for a long time placed second in importance to that of the Royal O'Briain. They were once styled Lords of Clancullen and the extensive territory over which they ruled comprised much of the present day Baronies of Bunratty and both Upper and Lower Tulla. The name is derived from "cu" meaning a hound and "na mara" of the sea, an example whereby the image of a legendary figure is incorporated into that of a surname. This important sept could trace their origin to Cas, the Celtic chief who settled here as leader of a group of people known as Dal Cais, thereby giving their name to the land of the Dalcassians.
Several references to the sept appear in both "The Annals of the Four Masters" and the "Annals of Inisfallen". They participated in several early warlike engagements relating to Inis Cealtra and Inis Cathaig which led to the defeat of the Norse; perhaps their most notable exploit was, at a later time, the successful storming of Quin Castle, then a formidable bastion of the Normans. Much credit therefore goes to Sioda Cam MacNamara for having years later converted the ruined shell of this castle into a great house of worship, with chapels, a sacristy and conventual buildings. So it was with pride and a sense of security that the Franciscans accepted the invitation to occupy this newly transformed building and where for the next two hundred years they were to live out their lives in prayer and austerity while ministering as well to the spiritual needs of the people in the best tradition of the Order.