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 Jan Hus Memorial stands at one end of Old Town Square. The huge monument depicts victorious Hussite warriors and Protestants who were forced into exile 200 years after Hus, and a young mother who symbolises national rebirth. The monument was so large that the sculptor designed and built his own villa and studio where the work could be carried out. It was unveiled in 1915 to commemorate the 500th anniversary of Jan Hus' martyrdom. The memorial was designed by Ladislav Šaloun and paid for solely by public donations.
Born in 1369, Hus became an influential religious thinker, philosopher, and reformer in Prague. He was a key predecessor to the Protestant movement of the sixteenth century. In his works he criticized religious moral decay of the Catholic Church. Accordingly, the Czech patriot Hus believed that mass should be given in the vernacular, or local language, rather than in Latin. He was inspired by the teachings of John Wycliffe.