CERN is where the Web was actually invented by Tim Berners-Lee, and they are celebrating it's 20th birthday this year. See their website here.
They also give a link to the document by which CERN put the Web into the public domain on April 30, 1993, which is what is making this the 20th anniversary.
Tip of the OOTJ hat to my good friend Roy Balleste for the alert! The image is a picture of Tim Berners-Lee running WorldWideWeb software at CERN in 1994, from the CERN webpage.