I’ll be in Montmarte next month. Where would that wall be, I’d like to see it.
It’s called the Communard’s wall. Here’s the Wikipedia entry:
https://en.wikipedia.org/wiki/Communards%27_Wall
It’s outside of the P’ere Lechaise cemetary. The rail line has a stop right outside it. I have to warn you, when you go there most of the visitors to the wall are going there to mourn. They might think you strange when you show up to celebrate victory over communism.
A few other things, if you are going to Montmartre you have to visit the Sacre Coeur church. It’s one of the most beautiful churches in France (possibly St. Michel is more beautiful) and at the foot of it is the most gorgeous view of Paris. You can see this Church from almost everywhere in Paris as it is the highest point of the city. Another thing to do is to visit Van Gogh’s house. He lived on Montmartre and his studio was there as well. The last very famous thing in Montmartre is of course the Moulin Rouge cabaret. The Le Chat Noir (Black Cat) was there as well.