At the Luossavaara-Kiirunavaara AB Mine, or LKAB for short, iron is quarried from the ground beneath Kiruna, Sweden. It’s the world’s largest underground iron ore mine and is run by one of the oldest mining companies in Sweden. The ore is mined from a few miles below the Earth’s surface using all sorts of high-tech and remote-controlled machines.

To extract the ore, a long horizontal tunnel is cut into the vein, the rock’s sheetlike slab of crystallized minerals. Holes are then drilled higher up and plugged with explosives that blow the whole thing into pieces. This exploded area then comes crashing down into the horizontal tunnel, leaving a large amount of smaller rocks that get pushed into sorters and conveyors to make their way out of the mine for processing.

You’d think this explosive subterranean worksite would be too dangerous to visit, but that is not the case. You can take a tour of the mine, where you and your group will go about 2.5 miles into the mountain, ending up about 1,476 feet below ground. The tour covers the mine’s early history up until the current day, and you’ll learn that each day, the mine produces enough iron to build six Eiffel Towers.

Even though the tunnels are well lit and ventilated, you can feel the warmth from the Earth, and the pressure is just enough to make you feel slightly uncomfortable. This sense of unease is intensified when the tour guide tells you that the actual operations are being done about half a mile below the surface from the visitor’s center, at a staggering 4,593 feet below ground. The visitor center itself is an actual old mine, full of contemporary and historical mining equipment.

Update as of July 2021: Tours are currently canceled.