English: The circular keep of Dinefwr Castle It is not clear whether it was the Lord Rhys or his son Rhys Grug who embellished the original ditches with the first masonry curtain-wall in the second half of the 12th century. The great circular keep is dated about 1230 and may be assigned to Rhys Grug. The castle was later transferred to English control with the last major work occurring in 1326. The castle was abandoned in the 16th century. In the late 17th century a summer house was built on top of the keep but by the late 18th century the site was once again a ruin. The Dynevor family maintained the site throughout the 19th and 20th centuries, rebuilding fallen masonry and erecting safety rails.