Old version of reveal (a tool that reveals tiles of a map in fortress mode), with updated memory.ini file. It does not require you to install anything (unlike the new version that can be found in Gibbed's Dwarf Fortress Tweak on DFwiki), just unzip both files and run reveal.exe while DF is running.
To reveal entire map designate the entire bottom level to be mined and then remove designation before running reveal. Playing on revealed map might cause some bugs (like not being able to build magma buildings).