Amazon's bubble-shaped botanical offices are now up and running. On Monday, the company announced the opening of The Spheres, the latest addition to its Seattle headquarters.

Amazon spent over $4 billion on the project, which was designed to create a rainforest-like environment in the middle of the city. The glass buildings are home to over 40,000 individual plants from over 50 countries.

But even as the structures function like an indoor botanical garden, they've actually been made for employee use. Amazon envisions staffers holding meetings at the site, which contain 40-foot tall tree houses in addition to sitting areas around the flora. The Spheres can hold up to 800 Amazon employees.

"Our goal with The Spheres was to create a unique gathering place where employees could collaborate and innovate together," said Amazon vice president John Schoettler in a statement.

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In total, the structures house over 300 different plant species. Most of them are from moist "cloud forest" environments found in tropical and subtropical regions. Over 25,000 of the plants have been woven into walls that run inside the buildings. There's also a 55-foot tall tree called a Ficus rubiginosa, which is the largest plant at the site.

The structures are a big change from the "outdated motels and surface parking lots" that original sat in the downtown location, according to the company.

Starting on Tuesday, the Spheres began to welcome Amazon employees. Unfortunately, the buildings aren't exactly open to the public. The company does plan on holding tours and field trips at The Spheres for local schools and universities. It's also created a visitor center at the site that anyone can book a time to check out.

However, some Twitter users are reporting the visitor center doesn't let you enter the botanical areas of The Spheres. Too bad.

This article originally appeared on PCMag.com.