From the trip this summer. These are the oven where the Sonderkommando were forced to burn their friends. Also called the The Grey ZoneĀ  (See quotation.), from the ashes of the dead. As the movie says:

I catch fire quickly. The first part of me rises in dense smoke that mingles with the smoke of others. Then there are the bones, which settle in ash. And these are swept up to be carried to the river. And last, bits of our dust that simply float there, in air, around the working of the new group. These bits of dust are gray. We settle on their shoes and on their faces and in their lungs. And they become so used to us that soon they don’t cough and they brush us away. At this point they’re just moving, breathing and moving like anyone else still alive in that place. And this is how the work continues.”

Published by Carlo Arioli