Coal mining: What is Ffos-y-Fran and why is it closing?
Ffos-y-Fran, the UK's last opencast coalmine, shut its doors for the final time on Thursday.
The mine, in Merthyr Tydfil in south Wales, is the size of 400 football pitches and 200 metres deep.
It has produced more than 11 million tonnes of coal since opening in 2008 and was responsible for 86% of the UK's total coal output in recent months.
The mine's operator, Merthyr (South Wales) Ltd, is meant to return the land to green hillside.
But documents seen by BBC News show concerns at the Welsh government and UK Coal Authority that it may be abandoned.
Merthyr (South Wales) Ltd said it was in "constructive dialogue" with Merthyr Tydfil council.