Subject to debate, but according to this article in the BBC, the claim of the “most valuable document in the history of the World Wide Web” belongs to a legal document that made the web publicly available in such a way that no one could claim ownership of it and that would ensure it was a free and open standard for everyone to use.
A team at the European Organisation for Nuclear Research (Cern) has launched a project to re-create the first web page.
The aim is to preserve the original hardware and software associated with the birth of the web.
David Galbraith wrote to Tim Berners-Lee, the inventor of the World Wide Web, who explained that the Web was was technically invented in France, not Switzerland:
I’ll bet if you asked every French politician where the web was invented not a single one would know this. The Franco-Swiss border runs through the CERN campus and building 31 is literally just a few feet into France. However, there is no explicit border within CERN and the main entrance is in Switzerland, so the situation of which country it was invented in is actually quite a tricky one. The current commemorative plaque, which is outside a row of offices where people other than Tim Berners-Lee worked on the web, is in Switzerland. To add to the confusion, in case Tim thought of the web at home, his home was in France but he temporarily moved to rented accommodation in Switzerland, just around the time the web was developed. So although, strictly speaking, France is the birthplace of the web it would be fair to say that it happened in building 31 at CERN but not in any particular country! How delightfully appropriate for an invention which breaks down physical borders. ]
There is a plaque in a corridor in building 2, but no specific offices are indicated and there is some ambiguity as to what happened where, in building 31. Thomas Madsen-Mygdal has a gallery showing locations in building 31 and 513, but there are very few places on the web documenting these places. I took photos of the plaque, such as the one here, with Creative Commons licenses, so that they could be used elsewhere.
Wikipedia is currently updated on the invention of the World Wide Web:
The first web site built was at CERN within the border of France, and was first put online on 6 August 1991:
“Info.cern.ch was the address of the world’s first-ever web site and web server, running on a NeXT computer at CERN. The first web page address was http://info.cern.ch/hypertext/WWW/TheProject.html, which centred on information regarding the WWW project. Visitors could learn more about hypertext, technical details for creating their own webpage, and even an explanation on how to search the Web for information. There are no screenshots of this original page and, in any case, changes were made daily to the information available on the page as the WWW project developed. You may find a later copy (1992) on the World Wide Web Consortium website.” -CERN