In the middle of the quest to acquire Twitter, Elon Musk’s other company, The Boring Company, has announced the completion of its Series C funding round.

The Boring Company (TBC), which aims to decongest land transportation by building underground highways, has raised $675 million, bringing its valuation to $5.7 billion.

According to the statement posted on the company’s website, the funds gotten in the round will be used “to significantly increase hiring across engineering, operations, and production to build and scale Loop projects, including Vegas Loop and others, in addition to accelerating the research and development of Prufrock and future products.“

The Prufrock is a line of next-generation tunnel boring machine that is designed to construct massive infrastructure projects “in a matter of weeks instead of years,” at a “fraction of the cost” and are capable of operating remotely and autonomously.

“Prufrock is designed to “porpoise,” meaning it launches directly from the surface, mines underground, and re-emerges upon completion. This allows Prufrock to begin tunneling within 48 hours of arrival onsite, eliminating the need to excavate expensive pits for launch and providing the capability to ultimately retrieve the machine for rapid reuse.” TBC explained.

“In the short term, if each Prufrock-2 mines at 1 mile/week, and TBC produces 1 new Prufrock machine per month, then TBC will be introducing 600 miles/year of capacity. As a point of reference, less than 20 miles of underground subway tunnel has been constructed in the United States in the last 20 years,” TBC said in a statement.

TBC said in October that it had recently received approval to build a 47km tunnel network which will connect 51 stations under Las Vegas. The company added that the project would be the “largest subsurface transportation project,” and will eventually be capable of transporting 57,000 passengers per hour through it.

The round, which was announced on Wednesday, had lead participations from investment firms like Vy Capital and Sequoia Capital. Further participation came from Valor Equity Partners, Founders Fund, 8VC, Craft Ventures, and DFJ Growth.

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Musk has continually been in the news, lately. The billionaire who heads the space exploration company, SpaceX; electric vehicle (EV) company, Tesla; and neurotechnology firm, Neuralink, had earlier this month become the highest shareholder in Twitter, after buying 9.2% of the micro-blogging site.

Musk had also gone ahead to offer $43 billion for the outright purchase of Twitter, a move which Twitter board responded to by adopting the “poison pill” strategy to avoid an hostile takeover. There are speculations, however, about whether Musk would be able to pull-off the funding required to much such large bid for Twitter.

Reports also have it that Tesla’s revenue leaped 81% and the end of the first quarter, exceeding analyst’s projections, and sending the company’s shares up more than 7% in after-hours trading.

TBC added that it is hiring talents for numerous roles. Those interested can fill up an application at boringcompany.com/careers.