Built around 1580 by the O'Connor family, who controlled this strategic stretch of coastline, the tower house served both as a fortified residence and a statement of authority during turbulent times. The castle's position overlooking Liscannor Bay wasn't chosen by accident; it allowed the O'Connors to monitor maritime traffic and collect tolls from fishing vessels whilst keeping watch for potential raiders approaching from the sea.

The castle follows the typical design of Irish tower houses from this period, with thick limestone walls, narrow defensive windows, and multiple floors connected by a spiral staircase built into the wall's thickness. What makes Liscannor particularly interesting is its relatively intact state, allowing visitors to appreciate features like the murder hole above the entrance, where defenders could rain down unpleasantries on unwelcome guests, and the remnants of the bawn wall that once enclosed a courtyard. The structure originally stood four or five storeys high, though the upper levels have partially collapsed over the centuries.

After the Cromwellian conquest of Ireland in the 1650s, the O'Connors lost their lands and the castle passed through various hands before eventually falling into disuse. Local folklore tells of a tunnel connecting the castle to the nearby cliffs, supposedly used for smuggling or quick escapes, though no evidence of such a passage has been found. Today, the castle sits on private farmland but remains visible from the road, its weathered walls still defying the Atlantic storms that have battered this coastline for over four centuries.