I've noticed this 'house' outside the front of the Gare du Nord on a couple of occasions, and at last I took the time to find out what it is all about. It's a sculpture, installed in 2015 and designed by the Argentinean artist Leandro Elrich. Its aim is to highlight the effects of global warming, hence the house appears to be 'melting'.
Very cool sculpture. You are making me want to visit Paris! I am not a big fan of cities but you are showing that there's lots to see and do away from the tourist traps.