Lludd is the celebrated King Lud, brother to Caesar's opponent Cassibelaunus. The Mabinogi, the Brut and Geoffrey of Monmouth record his fortifying of the City of London, stating that it was afterwards called Caerlud, later corrupted into Caer London, then into London, and lastly by the foreigners into Londres. They also state that King Lud was buried near the gate, still called from his name in the British language, Porthlud, and in the Saxon, Ludesgate.
   Among the poems attributed to Taliesin, is one called "Ymarwar Lludd," "The Conciliation of Lludd," in which the meeting with Llevelys from the Mabinogion is mentioned. Llewelys the Bard, in an ode to Llewelyn ab Iorwerth, refers to this occurrence, but in so cursory a manner, as not to throw any further light upon the subject. The imprisonment of the Dragons in Dinas Emrys in the Mabinogion of 'Lludd and Llevelys', is one of the most curious legends of romantic fiction. Their combats, five centuries later, led to the discovery of the enchanter Merlin, with which opens the great drama of Arthurian Romance. The story in Geoffrey of Monmouth's Hisotria has by many been considered as a fabrication; but it is also found in Nennius, who wrote in the eighth century, and of whose works, some copies as old as the tenth, are still extant. The substance of the tale related to us by Lady Guest is as follows:-
   "Vortigern being forced to retire from his kingdom, in consequence of his various delinquencies, took refuge in Snowdon; and finding Dinas Emrys an eligible spot, commenced building a tower there. But, to his great dismay, he found that whatever he built in the daytime, always fell down in the succeeding night. Having consulted his magicians upon the cause of this mystery, they told him that unless he could find a child without a father, and sprinkle the tower with his blood, it would never stand. Upon this Vortigern despatched messengers in every direction to search for the required victim, and at length they lit upon Merlin, whom they brought to Vortigern, that he might be slain. But the boy exposed the ignorance and imposture of the magicians, and caused the ground to be dug at the foundation of the building, where they found two sleeping dragons, one white and the other red. These dragons awaking from their sleep commenced a furious conflict. The white one at first had the advantage of the red, but at last the red dragon prevailed, and expelled his opponent. Merlin then informed them that the red was the British dragon, and the white one that of the invading Saxons.
   Then it was, according to Geoffrey and the Brut, that Merlin uttered the celebrated prophecy concerning the fate of Britain. Vortigern departing thence to seek some other place of refuge, bestowed that citadel upon the wonderful child, who declared his name to be Merlin Ambrosius, and after whom the spot was called Dinas Emrys."
   Whatever date or origin may be assigned to this legend, it is well known that the red dragon has long been the national standard of the Welsh. Henry VII bore it at Bosworth, and afterwards established the heraldic office of Rouge Dragon in honor of the occasion.
   Dinas Emrys, the site of all these marvels, is a natural mound, a small insulated hill in one of the valleys of Snowdon, between Beddgelert and Capel Curig. Giraldus Cambrensis speaks of it, saying, "At the head of the Snowdon Mountains, not far from the source of the Conway, which flows from this region towards the north, stands Dinas Emrys; that is, the promontory of Ambrosius, where Merlin, sitting on a rock, prophesied to Vortigern."