This iconic portrait of Billy the Kid is known toe Wild West fans at home and abroad.

But now, experts say, this photo from the summer of 18 78 was taken two years before.

It's the Holy Grail of not just Western photography.

It's the holy Grail of photography.

It is the rarest photograph in the world.

Ah, Holy Grail is something that is very important and desired, but difficult to get.

Now, when you hear the words Holy Grail, you will know with these news words mean.