I have never visited Auschwitz, but have visited Oradour -sur - Glane, France's ghost town which was machine gunned and burned by Nazi troops on June 10th 1944, four days after D.Day. The reason for the mass killings is still unclear, but after the war General de Gaulle determined that the village should remain exactly as the Germans left it, and so it eerily is, bullet holes, and burnt walls in the church where women and children were herded and mown down or burnt to death trying to escape. The men were tortured and executed, the village set on fire.
There is a museum too, with childrens' shoes, toys, prams, kitchen cutlery and so on, a Citroen car is parked where it's owner left it. You can feel that something appalling has happened here.