The estate, which takes its name from the Irish 'Ros an Fharraigh' meaning 'wood of the sea', encompasses both a medieval tower house and a later Georgian mansion. The original castle dates from the 15th century, built by the Rothe family who were prominent merchants in medieval Kilkenny. Its strategic position on elevated ground provided commanding views over the river valley below, making it both a defensive stronghold and a statement of wealth and power.

The estate underwent significant transformation in the 18th century when the Agar family, who later became the Earls of Normanton, acquired the property. They constructed an elegant Georgian house adjacent to the old castle, creating an architectural dialogue between medieval and classical styles that characterises many Irish estates. The demesne was carefully landscaped with woodland walks, formal gardens, and tree-lined avenues that survive to this day. During the 19th century, the estate expanded to over 1,000 acres, featuring a walled garden, ice house, and various follies typical of the Victorian passion for ornamental landscape features.

Today, Rossenarra Demesne offers visitors a chance to explore layers of Irish heritage in one location. The contrast between the austere medieval tower and the refined Georgian mansion tells the story of changing tastes, fortunes, and social structures across five centuries. The woodland paths that wind through the estate follow routes established generations ago, whilst the mature trees; some dating back over 200 years, create a living link to the estate's Georgian heyday. Though privately owned, the demesne's historical significance makes it an important piece of Kilkenny's cultural landscape, representing the complex relationship between Anglo-Irish estates and the communities that surrounded them.