The first-floor great hall had an ornate fireplace. William's son Maurice is credited with building the oblong keep; it is perhaps the oldest Norman keep in Glamorgan. Situated north of the main gateway, the keep was the first masonry building and was probably built in the 1120s. It is both the castle's tallest surviving building, and one of the oldest buildings in South Wales. Though only three of the original walls survive, their structure is characterized by irregularly shaped field stones, glacial pebbles, Lias limestone slabs, and brown mortar. Thomas de Londres replaced a timber palisade with a stone wall in around 1200. In the early 13th century, a second storey was added that housed private apartments. Garderobes were featured on two levels and a latrine tower was part of the exterior. A well-preserved lime kiln was built over an indeterminate 13th-century structure. Subsequently, a courthouse dating to the 14th century and rebuilt in the mid-15th century, was probably the third building to occupy the same spot. The building was rectangular in shape with a simple doorway and was flanked by two chambers. Having sustained damage during Owain Glyndŵr's revolt, a new courthouse, situated in the castle's outer bailey, was built in 1454 and was in use until at least 1631. The present-day castle remains consist of the keep and some outer walls. Grounds A deep, rock-cut ditch surrounded the castle grounds, which were dry except when the River Ewenny flooded the area during high tide. While the ditch that enclosed the castle's inner bailey filled at high tide, the flow was regulated by an embedded stone wall that blocked rising waters so that the interior of the castle did not flood. Looking towards the sea from the castle ruins, the view includes sandhills that proceed up the coast nearly as far as the town of Briton Ferry. Opposite from Ogmore Castle is Merthyr Mawr, where there are two sculptured crosses; the village can be reached by a footpath from the castle. Also near the castle are a popular set of stepping stones across the river which are a Scheduled Ancient Monument. A short distance to the southeast are several shallows filled with water that are said to have sunk spontaneously. One of them is circular, measuring approximately in diameter. Y Ladi Wen The ghost Y Ladi Wen ("the White Lady") is said to guard the castle's hidden treasure. In