It was much more than the Ghetto that got entirely destroyed, to the point where new street layout has been implemented after the war since there was no reason to use the old layout. Well, apart from property claims, some of which are still being contested in courts to this day. Around 150k to 200k people died in the Warsaw Uprising alone. But yes, the Ghetto got hit especially bad.

One of the reasons why the Germans wanted Warsaw so exceptionally destroyed was their feeling of racial superiority. The Fuhrer got extra angry when he found out those occupied Poles still dare create rebellions, and ordered a systematic levelling of the capital. I'll let you ponder whether we've actually learned a lesson from those times.