Like most young people in the Bay Area, Mike Kim grew up believing that the future of technology was being forged in Silicon Valley. Raised in Piedmont, an affluent suburb of Oakland, Kim was in college during the rise of Facebook, and he watched in amazement as tech start-ups transformed the world around him. After graduating in 2006, he found work in the industry, at Zynga, Monster.com and LinkedIn.

Then, five months ago, he accepted an offer to work for Woowa Brothers, a South Korean company that runs a food-delivery start-up called Baedal Minjok. The job was great — but living in Seoul was nothing less than a revelation.

“When I was in S.F., we called it the mobile capital of the world,” he said. “But I was blown away because Korea is three or four years ahead.” Back home, Kim said, people celebrate when a public park gets Wi-Fi. But in Seoul, even subway straphangers can stream movies on their phones, deep beneath the ground. “When I go back to the U.S., it feels like the Dark Ages,” he said. “It’s just not there yet.”

While Silicon Valley is the largest and most enduring locus of tech innovation, a number of cities around the planet are nipping at its heels: Tel Aviv, Berlin, Bangalore. But Seoul, the capital of South Korea, is in a sense the Valley’s closest rival. American investors are beginning to catch on, and venture capital is starting to flow west, across the Pacific. An early-stage American venture firm called 500 Startups recently spun off a small fund called 500 Kimchi, which focuses exclusively on South Korea. Last fall, Goldman Sachs led a round of investment in Woowa Brothers and its delivery service. In May, Google opened a campus in Seoul, its first in Asia. The office is in the trendy district of Gangnam — yes, that Gangnam — which is already home to a growing cluster of mobile start-ups and a handful of technology incubators to mentor them.