What happened in Aberfan on 21 October 1966?published at 08:34 BST
08:34 BST
It was the last day before half term, and pupils had just sat down to lessons at Pantglas Junior School in Aberfan.
Just after 09:00, a colliery spoil tip above the small mining community collapsed.
About 150,000 tonnes of slurry slid down the mountain and towards the village, engulfing the school and nearby houses.
The disaster claimed the lives of 144 people, including 116 children.
At the time, Aberfan, in Merthyr Tydfil county, was a village of a few thousand people, just like countless others dotted across the south Wales coalfield.
But its name is now ingrained on the national consciousness, and every year on 21 October, the nation pauses to remember those that were lost.
Stay with us as we bring you live coverage throughout the day as people gather in Aberfan to pay their respects.
Image source, Getty Images