This transformation, which was supposed to be temporary (the space was intended to return to its initial functions after completion of work on the theater in the 6th arrondissement), was carried out by the architect Jean-Loup Roubert.
The outside of the building, other from the glass door set in steel, the metallic awning and the red neon sign indicating the theater, has not been touched.
Without losing the industrial character of the building, the reception area and ticket office have been moved into the extension that dates from the 50's, a room in the Garnier building.
The design of the reception area is simply furnished in plywood, elegantly slipped into 10 meter high concrete screens that partition off the storage space. Canopies, also made from plywood, form a series of attractive niches at the foot of the storage space. Lighting and a heating system hang from the ceiling so they can be easily dismantled.
Between the reception room/ticket office and the theater, in the openings to the stage sets, small closed spaces have been constructed.
The theater auditorium is one large room, the storage space for sets and scenery having been demolished in order to free up space. Large metal beams have replaced the old, central, supporting pillars. The glass roof is covered by large panels that can be easily dismantled. The ground and the walls have been left in their original state and still bear traces from the past.
The theater's bleacher seats can also easily be dismantled, which allows for an infinite variety of configurations (stage or seating).
The dressing rooms are situated in a box at the top of the theater, the only architectural relief in the room.
In mai 2005, the Ateliers Berthier officially became the sister theater to the Odéon-Théâtre de l'Europe. New and more comfortable seating was installed. It is able to seat 395 (direct, front-stage seating).