ANTLR Download directory takes you to a list of files.
Currently you want:
antlr-3.0b7.tar.gz for ANTLR3
and
antlrworks-1.0b11.jar for ANTLRWorks the GUI editor.
See http://www.antlr.org/download.html for the latest version.
ANTLR Download directory takes you to a list of files.
There is a mirror of the development source at github