The current version is 5.3.16, released on Dec 28, 2014
Therion for Windows [13 MB] installs everything necessary to run Therion.
Therion packages for other platforms (not maintained by Therion authors): Debian GNU/Linux
Therion Digital Cave Maps: an article presented on the 4th European Speleological Congress
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.