fortune_articleAirbnb’s Brian Chesky shares the top spot in this year’s Fortune 40 under 40 with Uber CEO Travis Kalanick. Both companies have faced their share of controversy, but are influential in the built environment and the “sharing” economy, particularly as both look to expand internationally.

Fortune editors write of the number one picks, “They’re revolutionizing different ­industries, but this was the year Kalanick and Chesky became the figureheads for the ongoing clash between the potential of the Internet economy and the rules and regulations of the old economy. In the Internet economy the web can connect us to networks in which we can help ourselves to extra inventory, whether it’s a spare bedroom in someone’s house or a driver for hire idling between jobs. In the real-world economy, that ability can collide with entrenched interests and decades-old laws and regulations, as these two CEOs are finding. Kalanick’s style is to enter a market and ask questions later; Chesky is more diplomatic. What they have in common: growth.”

Mark Zuckerberg is no slouch at number two on the list, with Facebook driving much of the redevelopment around their Bay area offices.

Lyndon Rive of SolarCity is another rising star to follow as solar becomes increasingly integrated into buildings and homes.

Other real estate ‘moguls’ include Ivanka Trump, executive vice president of development and acquisitions for the Trump Organization (32), Robert Reffkin, founder and CEO of online real estate marketplace Urban Compass (35) and Sam Nazarian, CEO of SBE, a real estate company that focuses on hotels, nightlife and restaurants (27).

Urban Land will be unveiling their own 40 under 40 based on ULI member nominations at the Fall Meeting at the Javits Center in New York City.