Travel booking site GoEuro has raised $70 million in a new funding round led by top Silicon Valley investors – becoming one of the few European venture-funded firms to bridge the funding gap that stops promising start-ups from later stage expansion.
The latest round was led by Silver Lake Kraftwerk, the growth capital arm of private equity firm Silver Lake, and Kleiner Perkins Caufield & Byers. The two investors have backed a string of start-up successes including Skype and Spotify.
Berlin-based GoEuro declined to comment on where the fundraising leaves it in terms of valuation, but suggested in a statement that it was on track to attain coveted “unicorn” status, which refers to firms valued at $1 billion or more.
“GoEuro is now poised to join the small circle of European start-ups seen to have the potential to become multi-billion dollar companies,” the company said.
Get Term Sheet, Fortune’s daily email about deals and deal-makers.
The company said it plans to use the funds to expand its ground travel and domestic flight booking service to 30 countries in Europe from the 12 mostly Western European markets it serves, Naren Shaam, the company’s founder and chief executive said in an interview.
While search sites for airline travel abound, GoEuro specializes in hooking into the booking systems of ground transportation networks, which remain underdeveloped, with more than 80 percent of tickets still sold in local stations.
Travelers can book journeys with more than 500 European transport operators, including railway companies, bus operators and airlines offering flights within the region. The site provides a range of ground transportation connections.
“We are the largest source of information on ground transportation options in Europe. It is a huge barrier to entry,” Shaam said. The company enables travelers both within and beyond Europe to book tickets on their mobile phones.
“Many operators don’t have mobile applications. You should be able to click a button and hop on the next train.”
GoEuro says it attracts 10 million users a month to its travel booking app. That’s well less than a tenth of the audience of decade-old airline and hotel search site Trivago, but GoEuro is distinguished by its focus on ground travel.
For more on travel apps, watch Fortune’s video:
The site allows consumers to search in 12 languages, including Chinese and Russian, and nearly a third of GoEuro users are tourists from overseas, Shaam says.
Trivago, which was founded in 2004 in Duesseldorf and acquired by global travel site Expedia in 2012, is planning a U.S. stock market listing in coming months. It operates 55 travel sites worldwide.
GoEuro has raised $146 million since its founding four-and-a-half years ago. Last December, GoEuro raised $45 million from an arm of Goldman Sachs and top name European venture capitalists and entrepreneurs
