A very long time. So long that his wife forgot about him and slept with some other dude...I bet you don't even know who...starts with an L!
It doesn't matter I'm just glad he did or we wouldn't have Monty Python and the holy grail great movie!
Excalibar................The Holy grail...................Guinevere...........................The green night..........
Sir Perceval and Lancelot both attempted to obtain the grail, but neither was successful. Sir Galahad ultimately succeeded in finding the Holy Grail, and was permitted to gaze upon it, but never actually brought it back to King Arthur's court.
It sort of depends on whether you want to a direct answer or not. Directly, no Guinevere was not responsible for Arthur's death. I mean she was not the one who dealt the mortal blow but it was her and her affair with Lancelot that kept the Holy grail away from Camelot and removed Camelot from it's protection. So in a way Guinevere set the stage for Arthur's death at the hands of his son/nephew Mordred.
Sangreal
Well, not really. For one, the biggest problem is people who search for the grail don't know what it really is. There are lots o possibilities of what the holy grail might be. So nobody ever recorded finding it. Many orders and groups proclaim they have the holy grail but nothing can be proven. So to answer your question, nobody knows, maybe somebody did, or it could still be hidden.
The chalice in King Arthur's tails was the Holy Grail.
In some versions of the legend, King Arthur and his knights search for the Holy Grail, but finding it is often left ambiguous or open to interpretation. The quest for the Holy Grail is a central theme in Arthurian legend but the outcome varies across different versions of the story.
King Arthur on one of his many quests
he was one of king Arthur's nights who found the holy grail
King Arthur is a legendary British leader who is associated with the Knights of the Round Table, the sword Excalibur, and his quest for the Holy Grail. He is also known for his role in defending Britain against Saxon invaders in the early medieval period.
win him and his knights honor
Only the pure in heart can find the holy grail.
Sir Bedevere
The story goes that they were looking for the Holy Grail.
King Arthur, Merlin, the Knights of the round table, Camelot and the Holy Grail.
Galahad, Bors the Younger, and Percival achieve the Grail... source: http://en.wikipedia.org/wiki/Bors
He set his Knights of the Round Table the quest to find the Holy Grail.