This will be a melancholy and nostalgic Christmas for the people of Bottrop, especially for the last coal miners and their families. Three days before Christmas Eve, the Prosper-Haniel coal mine — the last black coal mine in Germany — is set to close. German President Frank-Walter Steinmeier was gifted the last piece of "black gold" to be brought up and see the light of day.

The coal was initially stored outside for days, like here with the Prosper-Haniel tower in the background. Then it was usually taken by train to the nearest port where it was loaded onto barges or ships to be taken to consumers; a large portion of it was shipped overseas. German hard coal was in demand worldwide for its quality, as long as the price was right.

The work in the coal mine was not only well paid, the miners were also held in high esteem. Their dirty, exhausting and dangerous work welded the miners together. Even now, they all call one another mate ("kumpel"). Their solidarity and camaraderie were always a reason for professional pride as can be seen here in this photo taken in Bottrop's Prosper-Haniel mine.

The miner operators built housing for the miners in the immediate vicinity of the pits. In the gardens, workers often kept chickens and pigs. Sometimes they'd even find room for a pigeon coop. Meanwhile, these houses have become very popular. Having a garden in the city is no small luxury.

After World War II, many so-called guest workers from southern Europe and Turkey came to work in the mines alongside colleagues from Silesia and Masuria, both in today's Poland. Many of them decided to stay.

The 1950s and 60s were the highpoint of the Ruhr mining industry. And yet, the first cracks in the mining business model were becoming apparent. The coal, which was initially near the surface, soon had to be dug out deeper and deeper — up to 1,500 meters underground. That was very expensive and German coal gradually became less competitive on the international market.

For decades the Ruhr area was notorious for its bad air. If you lived near a coking plant, freshly laundered sheets would turn dirty if you hung them out on the washing line. The image here depicts a skyline of coal, smokestacks, and smoke in Oberhausen — not far from Bottrop. Today, few people in the area miss these consequences of the coal business.

Even after coal mining is discontinued, it will continue to play an important role in the lives of the people of Ruhr Valley. Time and again, the earth opens up and houses, roads or railway lines are badly damaged by the notoriously unstable ground.

In the last 150 years, the Ruhr area has sunk in places by up to 25 meters (82 feet). Without intervention, the groundwater would rise again, transforming the area into a huge lake. So the water has to be pumped out — continuously. This legacy is sometimes referred to as an "eternal cost" for the more-than-five million people who live in the Ruhr area.

The omnipresent mining towers have now been demolished for the most part. Huge areas of the former complexes have been made green. Many former industrial monuments — and there are plenty of them — have been transformed into amusement parks — the best example being the Zollverein in Essen, which is now a UNESCO World Heritage Site.