The castle at Knock was home to the Lynch family from 1421, when Walter Leyns first appeared in the records, until the late 17th century. The family’s fortunes rose and fell dramatically; Peter Lynch backed the wrong horse when he joined Silken Thomas’s rebellion in 1535, losing his lands temporarily, though the family managed to recover their holdings. By 1640, Garrett Lynch owned 590 acres here, complete with two castles, a mill, various cabins, an old chapel and a stone quarry.

The surviving tower house is a substantial rectangular structure measuring 10.1 metres east to west and 8 metres north to south, built with fine quoins and a defensive base batter. Entry is through a pointed doorway on the western wall, leading to a cleverly designed interior with multiple floors connected by a newel staircase at the northeast corner. Each level served different purposes; the ground floor featured embrasures with pointed windows and storage cupboards, whilst the upper floors contained living quarters with fireplaces, garderobes and defensive gun loops. The second and third floors were particularly well appointed, with multiple windows providing light and ventilation, though the original roof and parapet have since been destroyed, leaving only two chimney stacks rising above the south wall.

The castle’s military significance became painfully clear during the 1640s when it was besieged and captured by the Royalist Ormonde in 1642, then occupied by Cromwellian forces five years later. Despite Garrett Lynch’s loyalty to the Royalist cause, which cost three of his sons their lives, he never recovered his ancestral home after the Restoration of 1660. Instead, the property passed to Henry Jones, the Anglican Bishop of Meath, who took up residence in the castle from 1661. A later house was subsequently attached to the southwest corner of the tower, its various doorways broken through the original medieval walls, creating an intriguing blend of defensive architecture and more comfortable domestic accommodation.