The Holy Grail is thought to be the cup that Jesus Christ drank out of at the last supper, as well as the cup used by Joseph of Arimathea to catch Christ's blood as he hung on the crucifix (4).

This is a famous painting from 1470 depicting the scene when the Holy Grail was revealed to Arthur and his knights in the middle of the round table.(1)

This picture depicts a lady holding the "holy grail." The woman is a goddess of sorts and the dove behind her represents cleanliness. (2)
Robert de Boron was the first to introduce the Holy Grail into the Arthurian Legend during the late 12th century to early 13th century. It was the highest spiritual pursuit in Arthurian times. In different versions of Arthur, different people are the highest "grail knights". In Chrétien's
Percival, it was Percival's quest to find the grail. In
Le Morte D'Arthur Galahad is the chief grail hunter, though Percival and Bors are included in the quest. The grail quest is a common theme in literature, included in works by Tennyson, James Russell Lowell, Jessie Weston, and T. S. Eliot. (3)
The Gothic legend of the Holy Grail has been developed and traced in detail by cultural historians. First it came together in the form of written romances, thought to be derived from some pre-Christian folkloric hints, later in the 12th and 13th centruy. Percival was the center of the early grail romances, and were woven into the more general Arthuiran fabric. these grail romances were French, but were translated into other European languages.(5)
The Holy Grail has also been the subject of many modern tales. Arthur's knights quest for it in
Monty Python and the Holy Grail(6). Harrison Ford races to beat Nazis to the grail in
Indiana Jones and the Last Crusade.(7) Robert Langdon searches for the truth of the Grail in
The Da Vinci Code.(8) It is still a popular plot element in today's adventures.

(9) This another picture of what the Holy Grail would look like according to historians. A silver goblet with embedded diamonds and gold rings.
(10)In Le Morte d'Arthur, the three knights thats successfully complete the Holy Grail quest are Sir Galahad, Sir Percivale, and Sir Bors.

This is a picture of Joseph of Arimathea cathcing the blood of Jesus in the Holy Grail as potrayed in the Arthurian Legend(11)
The Holy Grail is ony of the most enduring legends in all of Western European literature and art. This Grail was seen as the cup from the last supper and the cup which was at the crucifixion and was there to recieive the blood coming from christ's side. The Holy Grail ended up in Britian from Joseph of Arimathea who brought it over. For centuries it was hidden in this location. (12)
As, "The Sangreal"
The Holy Grail was given the name, "Sangreal" in later works depicting it. The term Sangreal comes as a combination of one of two pairs of words: Saint Gréal (meaning Holy Grail) or Sang Real (Royal Blood) (13). This "Royal Blood" idea has been referenced and even satirized in more recent works involving the Grail, yet has also been used in interpretations of the Grail and its meaning.
Source:
(1)http://www.bbc.co.uk/history/british/hg_gallery_04.shtml
(2)http://www.illusionsgallery.com/holy-grail-L.jpg
(3)http://www.lib.rochester.edu/Camelot/grlmenu.htm
(4)http://www.lib.rochester.edu/Camelot/grlmenu.htm
(5)http://www.crystalinks.com/holygrail.html
(6)http://www.imdb.com/title/tt0071853/
(7)http://www.imdb.com/title/tt0097576/plotsummary
(8)http://www.imdb.com/title/tt0382625/plotsummary
(9)faculty.smu.edu/bwheeler/kinga/sangraal.gif
(10)
Le Morte d'Arthur by
Thomas Malory(11) http://www.pittstate.edu/engl/nichols/stassenjosephfangtblutchristi2.jpg(12) http://www.bl.uk/onlinegallery/features/mythical/grail.html(13)http://community.middlebury.edu/~beyer/dvc/37r.doc.