Rathgar, in the Middle Ages, was a farm belonging to the Convent of St Mary de Hogges, at present-day College Green. At the Dissolution of the Monasteries, Rathgar was granted to the Segrave family: they built Rathgar Castle, ownership of which subsequently passed to John Cusacke, who was Lord Mayor of Dublin in 1608. The castle remained in the possession of the Cusack family for over a century, but gradually decayed and was a ruin by the end of the eighteenth century. No trace of it remains today, though it is thought to have been located at present day 44-49 Highfield Road.