Tropismes is the name of one of the most popular bookshops in Brussels. You can find find in the smaller Galerie Du Prince. Without any doubt, they sell books of Victor Hugo; the shops specializes in (French) literature and art books. But according to the information on the map, there is another connection with the writer as well:
During his time in exile in Brussels, this was the place where his mistress, Juliette Drouet lived, and was visited almost every day by Hugo.
According to Wikipedia,
Juliette Drouet, born Julienne Josephine Gauvain (10 April 1806 – 11 May 1883) was a French actress. She abandoned her career on the stage after becoming the mistress of Victor Hugo, to whom she acted as a secretary and travelling companion. Juliette accompanied Hugo in his exile to the Channel Islands, and wrote thousands of letters to him throughout her life.
I have only recently discovered that even nowadays people live in the Galeries Saint-Hubert. Most of the inhabitants in these flats and apartments are artists and writers.