D&D was published towards the end of January, 1975 making this the 45th anniversary of D&D.

Read what Jon Peterson has to say about the 40th Anniversary and the 45th Anniversary.

Check out my series of blog posts from 2014 for the 40th Anniversary Blogging Challenge. I also made a video series about those same topics here.

2020 the 43rd anniversary of Holmes Blue Box, which TSR still has not released the PDF. You can get a cool 5e conversion of the dungeon, The Tower of Zenopus used as an example of play. It is called The Ruined Tower of Zenopus [Affiliate Link] done by Zak Howard of the blog Zenopus Archives over on GM's Guild.

You can read the companion blog post here.