I had assumed for a long time that the frame around the map is as far as you can go, and for a long time this seemed the case and I saw 'You can't go this way' messages.

However I am now exploring a new area of the map (I won't mention where to avoid spoilers) and I have been allowed past this boundary a few times, even finding named locations.

Is this normal for Fallout?

Anyone else finding the same?

Nah, it's just in that one area.

WAIT, WHAT? The map wall broke and the game spilled off of the map?

I TOLD Todd Howard this might happen when he hired that construction company that was under investigation for using substandard materials!

Seriously though. I believe this is a first. Up until now, the only way to get beyond the map was basically being transported to a different rectangular map as part of a DLC.

SW corner of the map has several locations beyond the map perimeter...bring your hazmat suit!

There is also a mod that disables the invisible walls. You can see that at one point the map was going to be a bit bigger. You can see where they scaled down a few times by where they placed barrier fences

Sorry, double post

It's part of the story. Nifty way of giving players the sense of "Here there be dragons."

And it is only that one area.

Actually, it sort of is. In both FO3 and NV, there were places on the map that you could wander beyond the (marked off) map boundary and find something interesting. FO4 has just taken that to the next level by sending you into that area as part of the main quest series.