Treago Castle is a fortified manor house in the parish of St Weonards, Herefordshire, England (grid reference SO48922396).
Built c. 1500, it was recorded as a Grade I listed building on 30 April 1986—based on its extant medieval architecture, quadrangle courtyard layout and defensive wall corner towers.
Originally the building was of a secure design, featuring a central courtyard and no externally facing windows.
Later, the courtyard area in the centre of the building was covered over in stages and new windows added to the outside walls, forming a more traditional house.
Mason's marks matching those at Raglan Castle and traced to William Herbert, 1st Earl of Pembroke, were detected following a visit in 1975 by the Chief Inspector of Ancient Monuments, A. J. Taylor.
At the same time, a modern 11-metre indoor heated swimming pool was added and other renovations were carried out including of a grand piano.