Richard Stallman's GNU Project Began 42 Years Ago With GNU Emacs and More
GNU Project announced almost 43 years ago (next month it's the anniversary)
While some sites focus on the kernel ("Linux") turning 35 there's also an announcement of a new release of Emacs.
"The original EMACS was written in 1976 by David A. Moon and Guy L. Steele Jr." Wikipedia says, "as a set of macros for the TECO editor, and in 1984, Richard Stallman began work on GNU Emacs, to produce a free software replacement to the proprietary Gosling Emacs."
It would be fair to say that, UNIX aside, a lot of the Free software "pieces" began in the 1970s. Indeed, naming GNU/Linux (with "GNU"), here's how "free software" is mentioned in this old paper ("Research on the Application of Open Source Software in Digital Library" by Zhaohui Wei):
Getting history right is very important. █
Context: GNU/Linux Did Not Start in 1991 and America Wasn't Discovered by Europeans
Image source: GNU Emacs