That is, airplanes.

In this world full of ice and snow, a plane full of modern technology was parked on a square-shaped ridge two kilometers away from Xia Ren, and the white paint on the surface of the fuselage was the same as the surroundings, making Xia Ren almost ignore the past.

Xia Ren and Lanaya glanced at each other and decided that no matter what, they would go over and have a look first.

It was most likely Professor Fude who drove the plane over, but after such a long time, the temperature in the mountains at night was minus forty or fifty degrees Celsius, and the wind speed of more than ten meters per second was enough to freeze any creature that dared to stay outside, they couldn't tell if Professor Fude had suffered an accident, or the worst outcome...... Is it possible that he has also become a monster?

But that plane was their only hope of survival, and no matter how risky it was, they had to try.

With the help of Lanaya, Natsuhito got back on the sled and came to the bottom of the ridge, but the rock face here was almost vertical, and there was no slope to climb, so they had to drive the sled around the rock face to try to find a way.

Half an hour later, they finally saw a ...... Ladder!

"Could it be that humans have lived here before?"

Lanaya couldn't believe her eyes as she stared at the long and narrow staircase, which spread forty-five degrees upwards to the end of her vision.

Xia Ren looked at the size of the stairs and frowned slightly.

There was no snow on the staircase, and there were signs of weathering, each of which was about forty centimeters high, which was seriously out of shape with a human being, and he once again remembered the mirage he had seen yesterday morning, the magnificent megalith, and its proportions were very much in line with this staircase.

That city, most likely built by the monsters buried in the snow.

"Anyway, let's go up and have a look."

Xia Ren said.

They leave the sleds in place, and the huskies are rigorously trained not to run around easily unless there is an emergency.

Xia Ren refused Lanaya's support, this staircase is very long, she is not injured, she has a better chance of survival, Xia Ren must let her conserve her strength.

He had broken at least three ribs, so he had to endure great pain every step he took forward, and at the same time he had to make sure that he had to walk steadily with every step, otherwise he would be crushed if he slipped his foot at such a height.

It took an hour and a half, and although he had been in the ice field for more than a month, Xia Ren's physical fitness had improved, but he was still sweating, and most of it was painful.

Lanaya was also uncomfortable, as the air was thin due to the high altitude, and she had to breathe harder to keep her body hydrated.

When the two of them finally walked the last step of the stairs and came to the huge rock platform, they were already so tired that their faces were pale when they saw the plane parked not far away, but neither of them cared about the fatigue, looking at the scene in front of them, and was speechless in horror.

Farther away from the plane, a ...... stands Walls!

The walls are about thirty meters high, made of rocks four or five meters long, and although they are far away, they can still see the mottled traces of time on its surface, and they don't know how long it has existed.

Xia Ren could be sure that what was in front of them now was the mirage that they had seen yesterday morning!

Even Ranaya can't comfort herself that this is what humans are doing, and even any sane and sober person can't agree that this magnificent and terrifying building, this building that has never been recorded before, this building that is difficult to achieve even with modern technology, will be the handiwork of human beings!

Xia Ren barely suppressed the shock in his heart and came to the side of the plane.

The glass hatch with only two seats was closed, and it didn't take much effort for him to find the switch to open, but in the face of this pair of complex instruments and various dense and differently colored buttons put together, Xia Ren, who had never piloted an airplane, was dumbfounded.

"Do you know how to fly?"

He asked Lanaya a little stupidly, and she shook her head repeatedly.

"Then it can't be helped."

Xia Ren inhaled carefully to avoid touching the injury, and slowly climbed off the plane.

"The plane didn't look damaged, it should have landed normally, but there were no human signs around, and there was snow below, and no one could spend the night below without any camping, so we had to go in."

He said, looking at the magnificent city walls.

They had to find someone who could fly an airplane.

Lanaya was visibly terrified of this boulder city, but as long as she was with Xia Ren, she was not afraid.

This rock platform is probably just a side gate of the city, so the entrance is not too big, and the two of them hold hands and walk in nervously.

It is only when we are inside these buildings that we can appreciate our own insignificance.

The clear light projected from the ice clouds overhead illuminated the road, and around the two of them, there were rocks dozens of meters high, if the scientific research team was here, they could definitely deduce the approximate time of the existence of the city from the situation on the rock surface, but they were neither engaged in research, so they only felt a strong sense of vicissitudes.

Thanks to the previous mirage, Xia Ren knew the basic situation of the building in advance, and most of the walls inside were in the shape of a "positive", like a labyrinth of splicing, boundless, and they didn't go to a corner, so they used the broken rock at their feet to make a mark, so as not to get lost.

I don't know how long they walked, they began to see different buildings, such as ink-colored stones piled up together, showing irregular geometric shapes, and the two of them were frightened and quickly accelerated to leave; There are also smaller free-standing buildings with conical shapes, pyramidal shapes, and trapezoidal shapes, individual cubes, cube aggregates, and other cuboid structures, as well as the strange five-pointed star-shaped structures that Natsuhito had seen in the mirage scene, through which long circular arched bridges are passed through which it is not known where it connects or what it does. The city seemed to be a patchwork of various buildings, and it looked almost strange, but it was also possible that Xia Ren's own intelligence did not fully comprehend these buildings.

The further you go inside, the more and more incomprehensible things become, and the stone walls around you, which have been exposed to the cold wind for a long time, are full of devastation, and it is estimated that they were once glorious a long time ago, perhaps hundreds of thousands of years, or even tens or hundreds of millions of years ago, and the creatures that built them walked back and forth in them, exuding vitality.

Only now they are all in ruins.

Xia Ren also saw decorative carvings on the slightly better preserved stone walls, which were obscure patterns of lines, as elusive as the city's existence.

While they were looking at the inscriptions on one wall, a voice suddenly came:

"You are, humans?"