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:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.