When it's raining or too cold, they take their moving meditation inside the chalet.
Now, that option could be in jeopardy.
Joanne Drapeau, a volunteer tai chi teacher, says the city originally gave them the go-ahead to use the chalet more than two years ago, in part because they offer the class to the public for free.
"It's really a nice activity, and it's free," she said. "How many free things are there in this world?"
But last week, she got a call telling her the space is no longer available.
A spokesperson for the city says it has nothing against tai chi in particular, but decided to stop allowing organized activities in the chalet.
The city wants to keep the building open and accessible to everyone.
Drapeau says she is now looking for a new location but as she wants to avoid charging for the activity, it has to be free.
"All the places we tried before, they charge," she said.
"And we say, 'The city of Montreal, they have a beautiful space, it's an exceptional site, it's beautiful, it's underused, and we pay so much taxes, why not use it?"
Drapeau says the group has received nothing but positive comments from tourists — in fact, some have even stopped to join in.
"All the tourists that go by, they stop, and start practicing with us and they always say, 'Oh, I wish we had something like this at home.'"