Scribd, which one month ago launched a subscription plan to allow users to download an unlimited number of books for $8.99 per month, has hit a big milestone: 1 million books bookmarked by users.

To celebrate this latest milestone, the company, founded in 2007, built a gym in its San Francisco office, which it has added to a rock climbing wall, go carts, oh, and a zip line that runs straight into a kid’s swimming pool filled with balls — all provided by CEO Trip Adler to commemorate other milestones.

Today, Scribd calls itself a subscription reading service, with publishers such as HarperCollins, Rosetta, and Workman participating. I recently crashed at its office and discovered that although Scribd looks like fun and games, the company’s bottom line indicates it’s not. Could’ve fooled me, though, when I walked in the door for the first time.

Take a look: