The current version of Therion is 5.4.1, released on Apr 18, 2017
Source code [2 MB] compiles on Linux, Windows and MacOS X; requires some additional programs
Therion for Windows [16 MB] installs everything necessary to run Therion.
Development files: sources on GitHub & the current Therion for Windows [built on Apr 20, 2017 from the commit de9cfb8; 16 MB].
Therion packages for other platforms (not maintained by Therion authors):
Therion Digital Cave Maps: an article presented on the 4th European Speleological Congress
The Therion Book: the reference manual (included also in the installation packages)
See also the wiki pages.
Find out how Therion works on example data. It takes only a few minutes to
install Therion, run the example and get maps and model of the cave.
Padavka Chamber somewhat complicated real-cave example
Rabbit Cave plan and extended elevation
Example cave 1 rather simple example