Dungeon Designer 3 is an add-on to CC3+ for drawing floorplans of any type, above or below ground. The floorplans can include a customizable hex or square grid and can be printed at a precise scale (e.g. 1 inch = 5 feet), tiled over any number of pieces of paper.
The New Drawing Wizard lets you start floorplans in a variety of predefined styles, and you can choose dimensions and other map furniture. There is no built-in limit on map dimensions.
Dungeon Designer 3 has symbol catalogs for detailed, simple and tiled designing. In total there are more than 1000 symbols. Creating new symbols is straight forward, either with CC3+, or in most other graphics programs. Categories include Traps, Up and Down, Debris, Containers and Treasure and Wall Features. Symbols are smart, so a door can align to and cut a wall, and rocks will rotate, scale and be selected randomly.
DD3 includes a host of vector and raster based tileable fill styles for background, floors, grass, dirt and other terrain. DD3 has many drawing tools so that you can combine these together to build you maps. You can add caves, floors, walls, and rooms.
You can construct your flooplans by sketching out the rooms, and then connecting them with corridors which "lock" to the walls, optionally breaking holes. You can resize corridors on the fly, creating wide and narrow sections.