No name more chillingly sums up the bloody twentieth century than Auschwitz. The original concentration camp, housed in the red-brick barracks built for the Polish army in the 1920s, lies hidden behind forbidding grey walls on the outskirts of the sleepy provincial town of Oświęcim, an hour’s bus journey from Cracow. Nowadays, the mocking sign over the entrance, Arbeit Macht Frei, welcomes gaggles of tourists and students. The museum’s excellent guides explain everything with a calm objectivity that allows the full horror of what happened there to speak for itself. Nothing, however, prepares the casual visitor for Auschwitz-Birkenau, the massive death camp where more than a million Jews were systematically annihilated as part of the ‘Final Solution’ between 1943 and 1945. Situated a kilometre away, across the railway line, the infamous gateway stands incongruously close to some very ordinary modern houses. Such comforting signs of domesticity do little to overcome the sheer desolation of the place.

I was just such a casual visitor on my first trip there – a dull weekday afternoon with enough time to see the sights but not enough to absorb more than a few details. For my second visit, a couple of years later, I was fortunate to have my own guide, a German Catholic priest who has dedicated his life to prayer and interreligious dialogue at a centre in the old town. We did a sort of pilgrimage, silent and meditative, across the flat landscape, past the remains of the huts and the gaunt rust-daubed concrete posts that seem to run endlessly into the distance, and down as far as the trees that border the distant boundary, away from the buses and the tourist memorabilia. We inspected the ruins of the crematoria and paused before the abstract stone sculpture and the great bronze plaques that memorialise the victims who had been transported there from all over Europe. We saw the ponds where the ashes of the dead had been dumped, then looked at a set of photographs and read about what had happened on that precise spot more than sixty years earlier. It was there that the priest told me how he had learned to listen – as he put it – to the ‘voice of the earth’. Bending down he parted the rich tufts of grass and picked tiny traces of bone from the soil. ‘Terra sancta’, he said quietly to himself. It was as if the remains of the murdered millions were continuing to nourish our battered world. For him, Auschwitz was a deeply religious place because it preserved the most harrowing yet precious of memories.