Yeah, but that's clearly after-the-fact. :) Here's the oldest commit in Discuss, the conferencing system written for Project Athena:

https://github.com/mit-athena/discuss/commit/207670ad8bf752b...

That's an actual commit in RCS from 1986, which got imported to CVS, which got imported to SVN, which got imported to git last year. The entire history is now on GitHub:

https://github.com/mit-athena/discuss/commits/master

The codebase is still in use and still developed, although (as you might be able to tell from the recent commits) it's kind of old code. I've got one commit in there replacing a printf(s) with a printf("%s", s).