Current version is 5.3.11, released on Dec 22, 2012
Source code [3 MB]
compiles on Linux, Windows and partially MacOS X; requires some additional programs
Therion for Windows [13 MB] installs everything necessary to run Therion.
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