Elon Musk’s tunneling play, The Boring Company, has raised a $3 billion Series D funding round that pushes its valuation to $23 billion.

The round was led by the United Arab Emirates. The Boring Company said Thursday that it now plans to dig more than 150 kilometers of tunnels in the Middle Eastern country. Andreessen Horowitz, Sequoia Capital, Human Capital, Vy Capital, and Valor Equity partners also participated.

The Wall Street Journal reported in July that The Boring Company was looking to raise as much as $4 billion.

The Boring Company has done most of its digging to date in Las Vegas, Nevada, where it operates a handful of tunnels that connect hotel casinos and the convention center. It recently started work on a project in Nashville, Tennessee that will involve a 10-mile “loop” underground.

The company has stated that its goal is to “solve traffic” by moving vehicle travel into an underground, three-dimensional network of tunnels.