Do Shanks or Buggy know the location of the One Piece? Both Shanks and Buggy were apprentices on Gol D. Roger's ships. I had this doubt that whether they know the location of One Piece, shouldn't they know considering they were on the ship?
As stated on the wiki 


  Aside from the Roger Pirates and Whitebeard, before their death, no one actually knows where the great treasure is. source


This would mean both Shanks and Buggy would know the location of the One Piece. According to the information the most likely also know what the one piece is  Sort of a spoiler


  Given the recurring theme of treasure being something of great personal value (for example Luffy's hat), One Piece may simply be an item that Gol D. Roger valued. In Buggy's flashback to his days as a member of the Roger Pirates, he discussed with Shanks the meaning of a treasure, and he found that all the crew shared the same views regarding personal value  Vol. 3 Chapter 19 (p. 8)


As to the location they described


  It is said that it was hidden somewhere deep in the Grand Line, presumably in the last island, Raftel, by its deceased owner, the Pirate King Gol D. Roger