The Louvre opened to the public on 10 August 1793

avirose, was The Louvre the first public art museum?

Interesting! I did not know that!!

@ Kent -- Elias Ashmole donated his cabinet of curiosities to Oxford in 1677 on the condition that the collection be available to the public -- Oxford built the Ashmolean Museum and opened in 1683.
A lot of Elias' stuff had been burned in a fire between these two dates in January of 1679 at storage in the Middle Temple.
https://en.wikipedia.org/wiki/Elias_Ashmole

The trickier part is understanding that what we mean by 'the public' is not the same as what other eras and societies meant by the term, and also that the world is more than European aristocracy :-) [for instance, in the decades around 1600 the Mughal courts in India would put fine jewelry and artwork on public display...]

Wow, thank you, avirosemail! That’s a tremendous history message, and so Happy Art Anniversary!

But when the Louvre was first opened as an art museum, was there a particular painting from among the original 500, that everybody just had to see? And was the Mona Lisa not part of that first collection?

For practicality, were “restrooms” available? The WC’s at the Louvre nowadays are some of the nicest in France.

Vive le Louvre!

Interesting question, Kent. Turns out that the Director of Museum Studies at U.C. Santa Barbara even wrote a book on the subject!

https://www.universityofcalifornia.edu/news/origins-public-art-museum

Great topic, Avi! Thank you!

Merci, Avi. Brilliant contribution (as usual).

P.S. In our family, on August 10th we go stargazing if the sky is clear because it is also “The Night of the Shooting Stars.”

Museums are always a great topic, thanks for the link -- if you follow the implications of Carole Paul's study, linked above, which relates to what I have in mind when I said that 'the public' is not what it used to be, you'll be led back to the subject of tourism and travel!
Between cabinets of curiosity and the rise of tourism, you find the seeds of a lot of modern upper class institutions.
https://en.wikipedia.org/wiki/Cabinet_of_curiosities
http://www.tourismstudies.org/about.htm

For the benefit of anyone considering a museum-oriented trip to Washington DC: The Smithsonian has not begun reopening its museums except for a couple of sites that are primarily outdoors (one of which is the National Zoo).

The National Gallery is partially open, but it is not part of the Smithsonian. You'll find lnformation about the status of the various Smithsonian museums at www.si.edu.

Thanks for the better info, acraven, regarding the Smithsonian selective reopening -- I had the PBS Newshour on in the background when I was typing the OP and thought it seemed like a notable coincidence...

Does anyone know if there are tours of the Louvre that focus on the building's history and not the art?

The museum offers a free one lasting 20 minutes:

" Beginnings of the Louvre"
https://www.louvre.fr/en/visites-guidees

Also "The Napoleons" for the Napoleon Apartments and long-gone Tuileries Palace.

The audioguide is now on a rentable Nintendo 3DS but my recollection of the previous electronic handheld guide was that it had a route and many recitations that explored the history of the construction of the buildings...