Amazon.com Inc has opened a rainforest-like office space in Seattle that it hopes will spark new ideas for employees.

While cities across North America are seeking to host Seattle-based Amazon's second headquarters, the world's largest online retailer is still expanding its main campus.

Company office towers and high-end eateries have taken the place of warehouses and parking lots in Seattle's South Lake Union district. The Spheres complex, officially open to workers Tuesday, is the pinnacle of a decade of development here.