Thats what Hitler asked his general when Allies & French were fighting against his troops in Paris.
These days am reading this book by Larry Collins & Dominique Lapierre, which relates the course of events in Paris during its occupation by Germany & its liberation during World War II.
These authors have written the facts with a personnal touch. As in they have actually had talks with many people involved in world war II & so the way they present facts is a little different from a normal history book. And many places they even mentioned what became of those people post war. This book is mostly on events in Paris & doesnt tell much about the rest of world war.
Like with any war, the civilian life during German occupation, is really sad & is poignantly described. They were occupied in 1940 & finally in 1944 they got liberated. Hitler, The German ruler was very keen on holding onto Paris [France], cuz it was in a very strategic position for his ambitions in the war & so he had given orders to hold Paris under any costs. He did not care how much destruction that involved. He had infact even given orders [& preparation were almost done] to destroy the economical/industrial structures, the bridges which connected the city, all the major structures, just everything to criple the city. This all during 1944, when the signs of resistance were starting to be seen.