Starting as a Wallfacer, his defection to the Three-Body Problem shocked the world.

The construction speed of the [Mirror Project] has increased dramatically after receiving support from PDC.

After a period of construction, the underground city of Los Angeles has expanded to cover most of the city's above-ground buildings.

The city above ground consists of six districts: Xigong District, Luolong District, Jianxi District, Chanhe District, Jili District, and Laocheng District. There are three underground districts: Luoyang District, Beigongye District, and Xingu District.

Luoyang District is the center of the entire underground city, mainly used to solve administrative and residential problems.

Interestingly, even though the entire underground city is only in its basic framework, people have already started buying and selling houses there.

Lin Xuan felt that these people were buying houses at a pace that was a bit too advanced.

The entire mirror project, from construction to residents moving in, will take at least another ten years, and whether it can actually be built is another matter entirely. Yet, people are already starting to pay for houses more than ten years from now.

But thinking about it, he could understand. The mirror project was being promoted by PDC, so its credibility was beyond question; it was much better than those developers of unfinished projects.

In addition, given the Three-Body Crisis, they will definitely launch an attack on ground-based structures first.

Although everyone knows that if the Trisolarans were to invade Earth, they would be destroyed sooner or later even if they hid in underground cities, that's just human nature—they feel a sense of smug satisfaction at dying a little later than others.

Lao Cheng is a forklift operator.

Because of the recent global financial crisis, he lost his job.

After losing his job, he tried applying for jobs at other construction sites, but he was rejected and didn't get any work.

This is the harbinger of a major economic downturn. All sectors of the economy are in a slump. Apart from the engineering projects managed by PDC, ordinary construction projects can't even pay migrant workers their annual wages.

However, the construction work undertaken by PDC mainly involves the aerospace field, which is a high-precision job, making it difficult for ordinary people like Lao Cheng to participate.

As fate would have it, Lin Xuan was about to begin construction of an underground city in Luocheng.

This gave many construction workers like Lao Cheng, who were unemployed and staying at home, an opportunity to earn money.

Immediately, people throughout Henan Province sprang into action, flocking to Luocheng to participate in the construction of the mirror project. The recruitment site for the construction team was practically a bustling market, packed with people everywhere.

Are there any civil engineering students, both undergraduate and associate degree holders?

"Me! Me! Hire me! I have a Level 2 Construction Engineer certificate!"

"I can work overtime!"

"I can work even more overtime than him!"

"Thirty laborers are coming to fill in the soil. Wages are paid daily. Those who want to come, get on the bus and give me your ID cards."

"Telecommunications, communications, are there any telecommunications engineers here?"

"Hey buddy, how about something automated?"

"Sure, come on!"

There are five most difficult problems to solve when building an underground city.

The first problem is the ventilation system. Lin Xuan is building an underground city, not the Qin Shi Huang Mausoleum. If the air in the upper level cannot circulate with the entire underground city, then the billions of people living there will be buried alive on the spot.

However, Wei Cheng had already solved this problem. His method was quite forceful. He directly calculated and installed several ventilation ducts in key locations to create a circulation system for the air. Later, Ding Yi added some devices similar to circulation fans to make the air circulation process more natural.

The second issue is landslides.

You can't keep building and end up hollowing out the foundation of Los Angeles. If that happens, the entire city will collapse from the sky, and the people in the underground city won't even need to buy burial plots.

However, this problem is not too difficult to solve. The design drawings provided by Lin Xuan and Wei Cheng clearly analyzed the stress points of the steel frame, and it can be reinforced by driving steel bars into the concrete on both sides.

The only problem is that we have to build and demolish at the same time.

First, dig a pit, then build a steel frame around it to secure it so it won't sink. Then continue expanding outwards, dismantle the steel frame, and build a new one. This process is repeated more than ten times, and the entire city area has only expanded by less than one kilometer. It's incredibly slow.

The third issue is energy. This was originally quite a thorny problem, since the methods of energy transmission consume a huge amount of money. However, after Ding Yi improved controlled nuclear fusion, this problem was no longer a major issue.

The fourth and fifth problems mainly concerned policy and funding. These two problems were actually resolved after the entire PDC misjudged the Trisolarans' reaction.

Like Project Stars, PDC is a scam. They sell underground properties to the public to make a quick buck. Whether the underground city will be requisitioned by the military, used as a defense base, or something else depends entirely on the actual situation.

After Lao Cheng used a forklift to transport the last batch of sand and gravel needed for backfilling, he could finally breathe a sigh of relief.

He parked the forklift, found a corner, squatted down, and lit a cigarette.

Upon seeing this, another person nearby quickly came over as well.

"One more for me."

Old Cheng turned his head and found that the person who came was a fellow villager from his village. Because he had injured his eye while working as a welder in a repair shop many years ago, everyone called him Blind Man.

But the blind man wasn't blind; he just couldn't look at the sun or some strong light, otherwise he would weep uncontrollably.

Old Cheng took a cigarette out of his pocket, handed it to the blind man, and lit it for him.

"Hey Mr. Cheng, you've really gone up to the top tier these past few days. Didn't you used to smoke cigarettes that cost ten yuan or more?"

Upon hearing this, Lao Cheng was immediately enraged.

"Come on, you're lucky if you can even smoke one. Guess how much a pack of this stuff costs now? Over twenty yuan, which is about five times the price of what it used to be."

"So expensive?" the blind man exclaimed.

"Otherwise, do you think that the price increase in the last two days is just the original price tag?"

"I said to the shop owner, 'Isn't the suggested retail price on these cigarettes four yuan? Why are you selling them for so much?'"

"The boss said he wouldn't accept the suggestion."

Today is Lunar New Year's Eve, but due to the sluggish economy, people are not in the mood, and the streets lack the festive atmosphere of the New Year.

Nobody watches the Spring Festival Gala anymore; people just turn it on as background music during New Year's Eve dinner.

Occasionally, fireworks light up the distant horizon, as if proclaiming humanity's beautiful wish to keep moving forward.

"Wow, fireworks!" Luo Congmin exclaimed excitedly, pointing to the fireworks in the sky.

Compared to other people living in this era, she is undoubtedly very lucky. She doesn't have to worry about the Trisolaran crisis three centuries later, nor does she have to worry about food and clothing.

Lin Xuan led Luo Congmin through the streets of Luocheng. Passersby exchanged New Year's greetings. Lin Xuan asked around and learned that Luocheng holds a lively temple fair every year during the Spring Festival, with all sorts of fun things to do.

Originally, the temple fair was supposed to open on the Lantern Festival, but because everyone is short of funds now, it has been moved to coincide with New Year's Eve, which also saves some unnecessary expenses.

Soon, the two saw a lantern riddle stall in the distance. The stall owner was a kind old man in his sixties. When he saw Lin Xuan and Luo Congmin coming over, he quickly greeted them.

Happy New Year! Want to try your hand at solving riddles?

"Let's do it once."

Lin Xuan reached into her pocket and casually tossed in a hundred yuan.

"keep the change."

The shop owner was delighted to hear this, as it was the first time he had ever seen someone so generous. He quickly took a lantern from his stall and read out the question inside.

What has four legs but can't move? Guess an item.

Lin Xuan smiled slightly. He already knew the answer to the riddle: it was either a table or a chair. But since he had brought Luo Congmin here to play, he naturally wanted to make it auspicious and let Luo Congmin guess.

Luo Congmin rubbed his head, thought carefully for a while, and then his eyes lit up.

"I know, it's my dad!"