How does my iPod touch 5g map my photos on the photo map when I don't have wifi or anything some of the places I take the pics?

So I know some of the places I take pictures do not have wifi or anything but they still are on the map exactly where I have taken the and I was just curious how the iPod knows where I take the pics even when I don't have a way for it to, like I could understand if I'm at a house and it has internet but like it knew where the concert I took pics was at and put them exactly on the map where I was but I know I didn't have internet anyways does anybody know? Just curious