Hyperloop One hasn't made a penny, but it's worth big bucks.

The futuristic transportation company announced Thursday that it recently closed an $85 million Series B-1 round. That brings the startup's total funding to $245 million.

And, according to Recode, the company's valuation is now a whopping $700 million. (A representative for Hyperloop One wouldn't confirm or deny that figure to Inc.) That's an extremely high number for a company that is still yet to prove its technology works at full scale. The company is not yet earning revenue, nor has it received approval from any government to begin constructing a passenger rail.

Still, Hyperloop One has probably made the most strides of any company looking to build the low pressure, high speed tubular system first proposed by Elon Musk in 2013. Hyperloop Transportation Technologies--a startup that, like H1, is based in Los Angeles--is also racing to create a working prototype, but that company hasn't yet shown its tech to the public. Hyperloop One last year demonstrated a small scale test run that reached about 400 mph. It also ran a full-size test earlier this year, with speeds topping out around 192 mph. The plan is for the hyperloop to reach speeds of around 700 mph.

Building out the technology might be the least challenging part of the equation. Internal Hyperloop One documents revealed last year that each mile of track in the U.S. could cost upwards of $100 million. All of the proposed routes--Hyperloop One is currently weighing 10 of them--are at least 200 miles long, which would mean a minimum cost of roughly $20 billion. For comparison, that's about the cost (in 2017 dollars) of the Big Dig, the 15-year project to reroute Boston's highway systems that concluded in 2006 and was likely the costliest transportation project ever; and it's several billion more than the projected total cost of New York's infamous (and still ongoing) Second Avenue Subway project.

Last week, Hyperloop One revealed it had narrowed down its search for its first route from an initial list of 2,600 submissions. Four of those paths are in the U.S.: one connecting Pittsburgh and Chicago; one in Texas; one between Orlando and Miami; and one running from Colorado to Wyoming. The other candidates are in Mexico, Canada, India, and the U.K.

Many of those submissions came from local governments, which is a good start: In addition to permission to dig and build, any hyperloop company will likely need the government to pick up much of the multibillion-dollar tab.

Investors in Hyperloop One's most recent round included Caspian VC Partners and OurCrowd.com. The company also has investments from Sherpa Capital, Khosla Ventures, and GE Ventures.

Hyperloop One said earlier this month it wants to build three full-scale railways by 2021.