Just north of the ridge summit of Cefn Bryn, there is a neolithic burial ground, known as 'Arthur's Stone' (Maen Ceti). Its name comes from a legend that the ancient British King Arthur threw a large stone from Llanelli which landed on this spot.
It is believed that during the Bronze Age Cefn Bryn was used extensively for ceremonies and rituals. Beneath the bracken on the hill over sixty cairns have been discovered. Most of these are likely to be no more than collections of stones cleared by local farmers; but just north-west of Arthur's Stone three prominent cairns have been excavated that prove their ancient role - the largest being Great Cairn, a circular heap of stones above a central grave.
References:The ancient Argos Theater was built in 320 BC. and is located in Argos, Greece against Larissa Hill. Nearby from this site is Agora, Roman Odeon, and the Baths of Argos. The theater is one of the largest architectural developments in Greece and was renovated in ca 120 AD.
The Hellenistic theater at Argos is cut into the hillside of the Larisa, with 90 steps up a steep incline, forming a narrow rectilinear cavea. Among the largest theaters in Greece, it held about 20,000 spectators and is divided by two landings into three horizontal sections. Staircases further divide the cavea into four cunei, corresponding to the tribes of Argos A high wall was erected to prevent unauthorized access into the theatron and may have helped the acoustics, but it is said the sound quality is still very good today.
Around 120 CE, both theaters were renovated in the Roman style.