The Holy Grail  

 Historically, the existence of the Holy Grail has never been proven..... but the legends about it abound.

CATHOLIC ENCYCLOPEDIA: The Holy Grail 

  The High History of the Holy GrailPRIMARY SOURCE DOCUMENT

 Holy Grail : Offers a massive archive of Grail images, as well as a probable history,  theories, a discussion group, articles, and related links.

 The Legend of the Holy Grail :  Cool site that tells the legend in concise terms.

An Introduction to Current Theories about The Holy Grail:  Some good information.

 Holy Grail - The Camelot Project : Explains the myth behind the religious object and provides links to poems written about it throughout history.

 The Holy Grail : History and legends of one of the most important relics of Christendom.  THIS IS A HUGE SITE.

 The Role of the Knights Templar in the Grail Legends :  Good information.  And you may need  The Knights Templar Preceptory Portcullis  , a site that explains the Knights Templar in history.

 Mythical Quest: Holy Grail

 The Story of the Grail : The legend is here.

 The Grail Legend: from ancient stories to Wagnerian opera : A multicultural look at the Grail in history.

 Parsifal and the Holy Grail : a knight named Parsifal and the retelling of the classic myth of King Arthur and the Holy Grail highlights its significance for the present age.

 Perlesvaus :  Nothing historical here, but it is cool story told on some media intensive web pages.  (Obviously, I just liked it.)