Final answer:
The apartment in question was previously occupied by the famous artist Pablo Picasso, who rented a studio at Bateau-Lavoir in Paris, a noted gathering place for avant-garde artists including Henri Matisse and patrons like Gertrude Stein.
Step-by-step explanation:
The apartment Bertrand is renovating had previously been occupied by a famous artist, specifically Pablo Picasso. In 1904, Picasso returned to Paris and rented a studio in the Bateau-Lavoir, a hub for artists and poets in Paris. This period was critical for Picasso's development and introduced him to other avant-garde figures such as Henri Matisse and the American expatriate writer-poet Gertrude Stein, who along with her brother Leo, were influential patrons of modern art.
The Stein siblings collected modernist artworks and hosted a weekly salon at their home at 27 Rue de Fleurus, which became a meeting place for renowned artists and writers, including Picasso himself.
Moreover, Paris in the early 20th century was a city of transformation, away from its medieval beginnings toward a modern urban center with wide boulevards and distinct social classes often living in vertical division within the same buildings.
This transformation provided both the subject and audience for the burgeoning art movements of the time. Hence, in the context of Arts, it is evident that Picasso's Bateau-Lavoir studio was a significant site of artistic development and exchange, directly related to Bertrand's renovated apartment's historical significance.