This stub page replaces the home page for ACL2 Version 3.3. The original website for that version of ACL2 is stored as a collection of gzipped files, here:

In particular, the distrib/ directory contains the ACL2 source tarball, at acl2.tar.gz.

The file index.html originally in that directory has been removed. It was a soft link pointing to file acl2-doc.html.