The buttery yellow ramparts encircling the center of Avignon stretch 2.6 miles and are notched with arrow slits and gaps for dumping boiling water or cooking oil on attackers below.

Over the centuries, the walls have protected popes and warded off sieges. They have been rebuilt by the 19th-century architect who refurbished Notre-Dame, Eugène Viollet-le-Duc, and have been decorated by the notices for plays since the summer theater festival began in the city soon after World War II.

And for the last four months, they have borne witness to the mass rape trial occurring in the modern courthouse just across the road and to its central victim, Gisèle Pelicot.

The night before the trial began in early September, a group of local feminists traveled around the city and pasted pieces of paper with letters on them to walls, in large collages. They contained messages for the accused men who would arrive to court the next day.

“Rapist, we see you,” read one along the lip of an arched gate through the wall.

“Victims, we believe you,” read another.

The feminists belong to a group called the Amazons of Avignon. Like other feminist collectives in France, they had been gluing up messages about violence against women around the city for years. But they picked up their pace after Ms. Pelicot pushed for the trial to be opened to the public.