The flames are fed by the Czech Republic's four brown-coal mining companies, which extracted 40.6 million tons of coal in 2013. That number is down about 7 percent from 2012, according to data from the Energostat association monitoring the Czech energy sector.

Vrsanska Uhelna and Severoceska Energeticka contributed a total of 10.2 million tons. Gerthner, the guide, pointed in the direction of a nearby village, Horni Jiretin. It stands on 750 million tons of coal-enough to keep the miners going for another 100 years.

But a plan to expand the mine by flattening the village has angered environmentalists, while conservationists are concerned that landslides caused by mining might endanger a nearby castle.

"I'm glad I got a chance to see it all. I've heard a lot about the castle," said Marta Galiova, visiting from the country's eastern mining region that is grappling with heavy pollution.

"I know what smog is like. I suppose there are cleaner kinds of energy," she said.

Coal mining is a hot issue in the EU member nation of 10.5 million people owing to a 1991 government resolution that set mine border limits. Industry lobbies would like to see them lifted.

The center-left Czech government says it will make a final decision later this year. One option it is mulling is to only lift the limit on a single mine that is far from inhabited areas.

The history of brown-coal mining in the Most region dates back to the early 15th century. To make way for mining in 1975, the city moved its church by 841 meters, earning an entry in the Guinness Book of World Records as the heaviest object ever transferred by rail.

The city boasts large artificial lakes located on former mines. The local airport, motor racing track, shooting range and cemetery all stand on former spoil banks.

The same is true of a horse track opened in 1997, where horses gallop on 237 million cubic meters of spoil piled up over 40 years.