Best free tool to draw/create dungeon maps?

What are your choices to create/draw dungeon maps in the style of Dungeon Crafter?



I'm really bad at free-hand drawing so i'm looking for a tool/program

similar to Dungeon Crafter which helps me make maps easily that are simple yet not barebones.



Any ideas?



Best regards,

PB



p.s.: No sophisticated web-apps please, those make my desktop crash.

Best free tool to draw/create dungeon maps?