The Guoliang Tunnel connecting the clifftop village of Guoliang, in China’s Henan province, to the outside world was carved by hand using basic tools like chisels and hammers, and is now referred to as the eight wonder of the world.

For centuries, the people of Guoliang, a small Chinese village perched atop a cliff in the Taihang Mountains, were virtually cut off from the outside world. The only way in and out of the village was the “Sky Ladder,” 720 steps carved into the mountains during the Song Dynasty (960-1279). This made it extremely hard to get things in and out of the village, so most of the 300 or so inhabitants considered moving away in search of a better, easier life. However, everything changed in 1972, when the village council decided to carve a tunnel through the mountains to finally connect Guoliang to the outside world.

“It was a tough life. Commodities from the outside world could not reach the village, and our fresh farm products could not be transported to other places,” 72-year-old villager Song Baoqun told Xinhua. “We had to limit the weight of pigs to 50 or 60 kg; otherwise it would be difficult to carry them down the mountain.”

Guoliang struggled economically because of its isolation, but the toughest challenge by far was getting a sick person to the hospital in time. If someone fell ill, eight people had to carry a stretcher down the mountain using the “Sky Ladder”, and then undertake a four-hour journey to the nearest hospital. Something had to change.

Despite having any experience or engineering knowledge, 13 of the strongest villagers in Guoliang volunteered to start work on the mountain tunnel. Using only rudimentary tools like chisels and hammers, they lowered themselves on the sides of the Taihang Mountains using ropes, and carved into the rock inch by inch. At the most difficult stage, the tunnel progressed at a rate of one meter every three days, but the important thing is no one gave up.

As the tunnel started to take shape, more villagers joined the fray, and within five years the 1,250-meter-lomg Guoliang Tunnel was completed. For the first time ever, the secluded village of Guoliang could be accessed by car, and that changed everything.

“In the past, hungry villagers envied those living on the plains. Now nobody wants to leave this clifftop village. We feel good about our home,” local man Shen Heshan said.

Soon after the impressive hand-carved tunnel was completed, Guoliang went from being a small village virtually no one even knew existed, to a bustling tourist destination. Located at 1,700 meters above sea level, it offers some stunning natural vistas, but it’s the tunnel that attracts most visitors.

Xinhua reported that entrance ticket sales in Guoliang reached 120 million yuan (about 17 million dollars) in 2018, and locals who once struggled to fill their bellies, are now business owners investing in hotels and other amenities for tourists. And it was all because of 13 brave men who proved that nothing is impossible.

Also known as the “Long Corridor in Cliffs”, the Guoliang Tunnel is considered one of the most dangerous roads to drive on, mostly because of how narrow and twisty it is. In reality, though, there is little risk of driving over the edge of the mountain.

The hand-carved Guoliang tunnel is reminiscent of another epic project – the Chinese man who spent 36 years digging a 10-kilometer-long water canal through three mountains, in order to bring water to his village.