"What is this?" Surprised, Takatsu reached out and touched the edges of the semicircular arches, and found that the incision was extremely smooth, and there were no marks at all, as if it had been cut with a sword. It is impossible to imagine that these places turned out to be a whole wall carved with the patterns of fairy beasts and exotic beasts.

Perhaps something more magical was the mechanism that silently changed when the attention of the three was drawn to the bronze table that rose in the center of the bronze disc, opening the nine arches on the bronze wall.

Because all the nine circular openings in the dome were closed, leaving only a small hole in the center, this caused the underground space to suddenly fall into darkness again. What is hidden behind the nine arches, if you don't go inside, you can only see the darkness like an abyss.

"Boom!" A voice sounded, and Gao Zhen blew out a "fire fold" in his hand. The tip of the barrel-shaped fire fold lit up with a dark red glow, illuminating a nearby area. This is a lighting tool made of papier-mâché, which is lit with fire and then blown out to illuminate for a long time. This thing was prepared by him in Hakura, and it was very convenient to use during his expedition.

He held the fire fold in one hand and the opening of the arch with the other, and looked inside, wanting to see the situation inside the doorway. Since these openings are so low that they can only be crawled through by adults, the high pillows are bent over and almost on the ground to look at them.

The dark red light reflected the darkness, and the three of them finally saw the situation inside. It was a long corridor, and the walls of the corridor were made of huge bronze bricks. Molten iron is injected between the copper bricks and the copper bricks, and they are welded together, which is very strong. The interior of the corridor was dim and dark, and there was a faint chill, and its entire direction was diagonally downward, and the end could not be seen clearly.

"It's strange that there's not a bit of dust in there, like someone is cleaning it regularly." Yi Shuihan reached out and touched the bronze bricks around the corridor, rubbed his fingers, and said with a frown.

"This road is very well built, and before we came, it was almost airtight, and dust should not be able to get in. Maybe we were the first people to come here, and after this thing was repaired, it was never opened again. He pondered.

"Look behind the other doors." Lai Ruoxue stood up slowly, pulled a high pillow and came to an arch next to her.

Digging inside, sure enough, as before, there was a bronze corridor that extended downwards behind this door. After a closer inspection, I found that it was no different from the corridor behind the door just now.

The same is true for the remaining arches, with a total of nine diagonal downward passages, each facing nine different directions outside the bronze disc. There is no end in sight to all the corridors, and there is no idea what is connected to the other end.

"Looks like a labyrinth...... "Takatsu thought for a moment and said softly. He pressed his ear to each arch, trying to feel if there was any wind or air. Disappointingly, though, this seems to have come to naught.

"Underground labyrinths? There are nine entrances in total? What is the end of that labyrinth? Yi Shuihan wondered.

"Hell, I guess." Lai Ruoxue's voice was very hoarse, and her tone was not quite the same as usual, it should be because of internal injuries.

"Come and see here." Gao Zhen suddenly shouted behind the two of them, and the two hurriedly turned back to find him examining the bronze table that rose in the center of the bronze disc.

The bronze platform is cylindrical in shape, and is exactly half the height of the entire underground space. Directly opposite its top is a small circular hole in the dome, from which a beam of sunlight shines straight above the platform. However, noon seems to be almost over, and the sun will soon be tilting.

The surrounding area of the round platform is carved with patterns, but unlike the carvings on the floor and walls, which are floating, the patterns around this round platform are hollow and carved. What's even more strange is that the carved things on the ground and the wall can at least be seen as fairy beasts and strange beasts, and the hollow carvings on the round platform can't tell what they are at all, they are intricate, entangled, and look like some ...... Some tentacles?

"What is this?" Yi Shuihan also felt strange, and he reached out to touch those weird hollow carvings. The inside of the entire round platform is hollow, and you can see that the sunlight left a small spot of light in it. The scene feels like a bronze cage that binds sunlight inside itself.

Wait, Yi Shuihan suddenly found something strange. If sunlight can shine into the inside of the platform, it proves that there is also a hole at the top of the platform, through which the sunlight shines in. He looked to the top of the round platform, and sure enough, there was a narrow crack in the shape of a diamond.

He rubbed lightly against the diamond-shaped crack, which was so smooth that it shone in the sunlight, making it slightly hot, not as cold as it was.

"This ...... Looks like something is going to be inserted? It's a keyhole! He hesitated for a moment, then suddenly came to his senses.

"But what about the key?" Gao Zhen also saw this, but he was struggling that he couldn't find the key.

"If the key is to be inserted into a hole in the round table, it must be as high as the round table, more than a meter long; And its cross-section should be smooth and diamond-shaped; He should also be able to sense the sunlight shining down from the dome...... "The high pillow combined with the structure of the keyhole roughly simulated the appearance of the key in his mind, and suddenly he felt that this imaginary key seemed to be somewhat familiar to him......

"Your sword!" Lai Ruoxue and Yi Shuihan suddenly shouted in unison, they pointed to the Void Condensation Sword behind Gao Zhen, and their faces showed joy.

"My sword?" Gao Zhen pulled out the long sword that sealed the strange immortal beast in confusion and held it in his hand. This long sword is indeed more than a meter long, the cross-section is diamond-shaped, the surface is unusually smooth, and its sword body is still a clear mirror that can reflect sunlight.

"Plug in and give it a try! It's almost past noon! Lai Ruoxue pushed the pillow. Indeed, if it were past noon, the sunlight that came down from the dome would no longer be straight and would not reach the diamond-shaped hole in the bronze pedestal.

Gao Zhen hurriedly raised the Void Condensation Sword upside down, aimed the tip of the sword at the diamond-shaped hole on the round platform, pushed it with his hand, and with a click, the Void Condensation Sword was inserted into it, and the entire sword body was submerged into the inside of the round platform, and the hilt of the sword was just exposed.

Observing the position of the "keyhole", it was surprising that the Void Condensation Sword actually matched the round platform. The diamond-shaped hole seemed to have been designed specifically for it, clinging tightly to the hilt. As for the length of the sword, it was just right, and the tip of the sword touched the spot of light inside the round platform, and it stood there steadily.

Then, something magical happened. The pillar of light that shot down from the dome shone on the end of the hilt of the Void Condensation Sword, and through the crystal-like transparent hilt and blade, it completely shone into the inside of the sword. The sword body of the Void Condensation Sword was composed of countless irregular mirrors, which constantly reflected and refracted the sunlight that shot into the interior, forming a complex path of light, and at the end, shooting out from one side of the sword body.

Through the refraction of the crystal-like Void Condensed Sword, the sunlight that shone down turned into a narrow band of light, shooting out from one side of the blade, piercing through the hollow carvings on the bronze round platform and projecting onto the ground.

Yi Shuihan and Lai Ruoxue hurriedly walked away and made way for the light strip. It was a golden fan-shaped band of light that was projected on the ground and stretched to the edge of the bronze disc. The hollow carvings around the bronze round platform leave a shadow on the light band, alternating light and dark.

Dark streaks are shown where shadows are obscured, while those that are not obstructed are bright. The intricate patterns and the reliefs of bronze discs on the ground form a map.

It turns out that the intricate dark stripes represent the movement of the corridor behind the arch.