Though what you see today is largely an 18th-century castellated structure with Victorian Gothic additions, the site has a much longer history. The original castle was built in the 16th century by the 5th Lord Trimblestown, only to be almost completely destroyed during the 1641 Rebellion.

When antiquarian Austin Cooper visited around 1781, he recorded an L-shaped castle with a fascinating inscribed stone set into a window at the northwest corner. The stone bore the Trimblestown family arms and noted that John, the 3rd Baron of Trimblestown, had served as Lord Chancellor of Ireland and lived in the castle in 1509. This detail suggests the site may have had an even earlier medieval structure, though the 16th-century castle is the earliest documented building.

The castle underwent a major reconstruction around 1794 under the 13th Lord Trimblestown, who essentially created the castellated building visible today. The Victorians couldn't resist adding their own touch in 1874, when a three-storey Gothic porch with battlemented gable was built onto the structure. This blend of genuine medieval remains, Georgian reconstruction, and Victorian romanticism makes Roebuck Castle a perfect example of how Ireland's historic buildings evolved through centuries of destruction, rebuilding, and reimagining.