I'm guessing that the building in the center of the map is where the Ceruleum core is. I noticed it has a stair case on both ends that lead up to the railroad tracks.

It looks a lot like you can climb this building and jump on the back of the train to catch a ride.




The Goblin Train looks to have some sort of platform that you may be able to jump/stand on.




Could be wrong, just pointing it out.