I am going to Ecobox with a few friends on saturday night (Marx Dormoy metro station).
It's a shared garden and there is a great view on Montmartre from their where we can watch the firework of "La fête des vendanges". The firework starts at 8:30pm. We can have drinks and food their also.
I think there will be some people playing music too. It's a great spot with an easy going vibe !
Come and join us if you like
It's outdoor so might be a bit cold depending on the weather.
You can pm message me for my number, I ll try to have a CS sign somewhere so that you can find us.