The tweet says:
if you came to the Labrouste Hall on Friday, please dm me.
At first I just dismissed it, and answered that no, that must have been another Robin Métral.
Later I looked up the Labrouste Hall, and wow:
(Photo by Adelphilos on Wikimedia Commons)
The Labrouste Hall is a reading room inside the Richelieu building of the French National Library (BnF). It's in Paris.
It was built by architect Henri Labrouste between 1861 and 1868—apparently using iron in architecture was his trademark, hence the lamppost-looking pillars.1
It looks great though.
(Photo by Paris 16 on Wikimedia Commons)
That's not all.
There is a pneumatic tube system that used to bring books to and from readers, similar to the one in the New York Public Library.2
There are 36 low reliefs of famous writers on the walls: Shakespeare, Corneille, Racine...
The hall originally didn't have any artificial lights, because gaz lighting was considered a hazard. Electric lamps were added in the 1920s to supplement the skylights.
The paintings of trees that you can see in the first picture were painted by Alexandre Desgoffe in 1864 to "induce a sense of calm and relaxation in readers".3
The Labrouste Hall is so full of mysteries, it makes me wonder...
What if the tweet wasn't a mistake? Could it have been the first clue of a treasure hunt? An invitation to embark on a National Treasure-style adventure?
Or maybe, a Robin Métral in Paris lost his notebook.