Ogmore Castle construction might have begun in 1106. It was in use until the 19th century for a range of purposes, including a court of justice and a prison, but is now a substantial set of remains and a local landmark.
The earthworks were steeply banked and oval in shape, enclosing an area of 50 m in length by 35 m in width. The inner ward was flat and constructed of timber structures. After completion of the ringwork, the building material was stone. The windows were round-headed with Sutton stone ashlar. 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.
The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.