As darkness thickened and the crowds drifted away from Auschwitz last night, a ribbon of fire still flickered beside railway tracks that carried a million to their death.
Hours earlier, with snow swirling through the barbed wire and torches burning in the freezing air, a ceremony of remembrance to mark the 60th anniversary of Auschwitz's liberation began with a ghostly prison train's whistle, and the clank of heavy doors opening to disgorge their doomed cargo.
In between, survivors of this Nazi death factory recalled those who died here, their blood and ashes mingled in the frozen earth, and the world's leaders vowed never to permit a repeat of what the Red Army discovered 60 years ago in this corner of southern Poland.
Swathed in fur coats, blankets and snow-dusted hats, Jews, Poles, Gypsies and other former inmates of this, the largest of Hitler's death camps, watched the President, Mrs McAleese, add her candle to dozens that glowed on the Holocaust memorial, as spotlights silhouetted skeletal trees and silent watchtowers against the darkening sky.
The Germans gave this killing-ground a name - Birkenau - for the birch trees that stand here in serried rows, beside barracks that gave squalid shelter to more than a million people, and the gas chambers and crematoria where they met their end.
This was the dark heart of a machine that dragged Jews to their deaths from as far apart as Greece and Norway, Russia and France, along with 500,000 Gypsies, 10,000 homosexuals and five million other soldiers, resistance fighters and civilians.
The gathering was perhaps the last time that so many survivors, most of whom are aged over 80, will join with a few of the remaining Soviet liberators of Auschwitz to remember the creation by the Nazis of an unprecedented production line of death - a place where the "Angel of Death", Dr Josef Mengele, decided in a moment whether each new arrival was worthy of slave labour, the gas chamber, or the benches where he performed his macabre experiments.
Here, hundreds of thousands of people were worked to death, their teeth then examined for gold, and their hair sent to textile factories back in Germany.
When the final candle had been laid on the cold stone of the memorial, a Polish choir sent a lament drifting out over the camp, above the dark hulks of its buildings and the gallows where Auschwitz's commandant, Rudolf Hoess, was ultimately hanged.
The train's whistle sounded again and fires erupted along the railtracks.
As they crackled and blazed, smoke hung in the air where once crematoria burned day and night to erase the memory of Nazi crimes - crimes that yesterday seemed close at hand.