 It is a Scheduled Ancient Monument, recorded as such by the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS).Originally known as Yestred (from the Brythonic "Ystrad", meaning strath or dale), the barony of Yester was granted by King William the Lion to Hugo de Giffard, a Norman immigrant given land in East Lothian during the reign of King David I.The original stone keep, built before 1267, is generally considered to be by Sir Hugo de Giffard.