So are you wanting to make a poster of a map you already made, is that it? If so, you might look into having one printed. I would think it would be less than 50 bucks.

If you want to make it from scratch however, well, I'm not sure. It's been too long since I attempted anything like that. Which does remind me, I have a huge dungeon on giant graph paper I should try scanning in and sharing.

Are you wanting to color the map or just black and white, as that means something else?