A Unesco World Heritage site in Poland is being used to help people recover from Covid-19, with patients going deep underground in the Wieliczka salt mine to a therapeutic centre dealing with respiratory illness.
Famous for its ornate underground chapels carved from salt, the Wieliczka mine, located just outside the southern city of Krakow, is one of Poland's biggest tourist attractions, drawing around 1.8 million visitors in 2019.
But doctors say the micro-climate in the mine, which stretches as far as 327 metres underground, also helps people with pulmunory problems.
Magdalena Kostrzon, a doctor working at the mine, told Reuters that patients with respiratory illnesses have been coming there since the 19th century.
"The underground micro-climate is, above all, characterised by exceptional air purity," she said.
"The air reaches here through a whole series of salt corridors... Thanks to this, it is cleaned of pollutants that are on the surface."
For Jozef Biros, 58, who caught Covid-19 in November, the benefits from his stay in the mine are clear.
"Two weeks have passed and I will tell you that I am feeling better and better, both with breathing and physically," he said.
"Even a simple thing like tying your shoes -- I used to bend down and feel I have no air, but now I can tie my shoes no problem."