Y Ddraig Goch
The Welsh flag is often called "Y Ddraig Goch" for it has a red dragon on a green and white field. The origin of this symbol is found in early Welsh legend and history, namely the Historia Brittonum, "Cyfranc Lludd a Lleuelys," and Historia Regnum Britanniae.
The red dragon symbolizes the original Britons (now the Welsh) as a sort of totem animal, as demonstrated in two related stories. The first, "Cyfranc Lludd a Lleuelys" (which is found in a later text than the second) says that King Lludd was oppressed by a shriek every May Eve. His brother Lleuelys informs him that it is two dragons, one representing Britain, the other representing an invading nation. Lludd buries the two dragons at Dinas Emrys, and puts the land at peace.
However, the second story--found in three sources, the Historia Brittonum, Historia Regnum Britianniae, and The Welsh Triads, we are told that King Vortigern wanted to build a fort at Dinas Emrys, and is told by Ambrosius (or Merlin in the HRB) that he must dig up the two dragons. At this point, the dragon of the Britons is identified as red, while the other dragon--which represents the Saxons--is white. Ambrosius/Merlin prophecies that the Britons will drive the Saxons back to the sea. (See Vortigern and the Dragons for the full story.)
The dragon was apparently originally a Roman emblem, later adapted by some British chieftains. The dragon came to symbolize the leader of the Britons--such as Uther Pendragon and his son Arthur. Maelgwn Gwynedd was called "Dragon of the Isle" by Gildas, and the symbol was also used by Owain Glyndwr and Henry Tudor before becoming the official flag of Wales.
One can also see the Welsh Dragon just outside of St. David's
, Pennsylvania, on the offramp of the Blue Route (I476), between St. David's and Bryn Mawr
. This is an area of Pennsylvania--the Main Line
just out side of Philadelphia
--which has a lot of Welsh nameplaces. The Dragon--made of stones placed to form the shape of a dragon--sits on one hill, while on the opposite hill is what looks like a a cairn
. Kind of an odd site on your way to work every day.