When Bran Ferren was 9 years old his parents took him to the Pantheon in Rome. He looked around at the marble and sculptures, which seemed typical in the ancient city, and then he looked up at the ceiling, which didn’t seem typical at all. It was high and dome shaped and at the top there was a small hole that let in a heavenly shaft of light.

“It was the first church I had ever been in that offered an unrestricted view of god,” he said. “That moment changed my life, and I remember it like it was yesterday. I realized that 2000 years ago people were smart.” The domed room was an engineering miracle because the dome was free standing, and it was an artistic miracle because standing in that room was a special experience.

What, asks Ferren, is the modern Pantheon-- a miracle of engineering and art that will likely still be appreciated thousands of years from now?

The former head of Imagineering for Disney and now Danny Hillis’ partner in Applied Minds, Ferren is as qualified as anyone to provide an answer. He actually posed the question himself, to the audience at the TED conference on today in Vancouver, and promptly answered it: Autonomous vehicles—self driving cars.

Cars that can drive themselves, says Ferren, will be the key innovation that allows us to redesign our cities and our world. They’ll save lives by making driving safer. They’ll cut pollution by making trips more efficient. They’ll reduce road congestion. They’ll recapture vast amounts of productivity lost while we sit in traffic spewing pollution from the tailpipes. And they’ll enable compelling new concepts in how we design the workplace.

Most of the engineering needed to make self-driving cars a reality has, he says, already been accomplished:

1) GPS delivers the ability to know exactly where we are at exactly what time;

2) Web-based maps give us the ability to know where the roads are, the rules for driving them and where we're going;

3) Wireless technology provides near-continuous communication with big supercomputers as well as surrounding cars and other vehicles.

The only other technological breakthrough that's needed is the ability for autonomous cars to recognize people, signs and objects. “We can do a lot of this,” says Ferron, “but a lot isn't enough when your families are involved.” Instead, a self driving car may not be completely autonomous—it may have to notify a human driver when it encounters an obstacle it can’t identify. “You may need to wake up your passenger to explain what that big lump is in the road,” he says. “But once you identify something, all other cars everywhere will know it.”

The coming of self-driving cars is only a handful of years away, he says, and they will permanently change our world in the next few decades.