Marineford is the Marine HQ and is located in the second half of the Grand Line. It was formally known as G-1 base.
The location of Marineford is a setting from the One Piece series that was written by Eiichiro Oda. The series first began serialization in Weekly Shōnen Jump on August 4, 1997. It first appeared in One Piece Volume ?? CH. 700 "His Momentum", and the anime appearance was in One Piece - Episode ?? "??".