Somewhere in Billund–a tiny town with a gigantic international airport in the middle of Denmark–there’s a magical place that you can’t visit. A fantastic chamber hidden from the public, buried under a house burned down and rebuilt twice by a man with a crazy idea. That man’s name was Ole Kirk Christiansen . And that crazy idea was one of history’s best–an invention that affected the lives of billions of kids around the world for decades to come.

I stumbled upon this secret room in 2008 while visiting the old Lego House. A quiet, elfish woman with a big smile walked me down a flight of black stairs to a locked vault and said: “This is where your childhood dreams rest.” And it was true. She let me in, and I touched those dreams with my own hands. Blue spaceships, yellow castles, white monorails; all sleeping for decades, spooning each other. Inside this room sat all the Lego sets that had made me happy for years.

Today, my childhood dreams rest elsewhere. It’s not as secret, or as magical, but the new Lego House, which has finally opened its doors in Billund, is a fan wonderland on its own right.

Designed by Danish architect Bjarke Ingels, the 129,200-square-foot center sits right in the heart of the city, replacing the old town hall. A gross case of corporate invasion of a public space? Perhaps. But when I was in Billund, it seemed like the entire town was already completely built around Lego. Even the street signage had Lego iconography on it. Billund saw Lego evolve, from its humble origins as a wooden toy shop in 1932 to its shift to interlocking plastic pieces in the ’60s to its current multinational corporation status. In a way, replacing the outdated bureaucratic building with the embodiment of the Lego company in architectural form is a metaphor of the town’s history, which saw itself grow from little village to international commerce hub thanks to the toy company.

The building is composed of 21 interlocking blocks, with stairs that allow people to climb to blocks’ roofs. It looks like a Lego Architecture set, right up to the circular skylights on the highest brick. In fact, the company is releasing a Lego Architecture set of the new building. (If you build it inside the real Lego House, it opens an inter-dimensional wormhole filled with demons–the same demons that visit parents’ homes at night to drop Lego bricks to be stepped on.)

According to Lego, its new visitor center contains lots of “experiences” for kids and adults. At its core, bathed in light, there is a fantastic stair built around a tree entirely made of Lego bricks. 6,316,611 to be exact. They call it the Tree of Creativity. I call it the Tree of If-I-ever-have-the-money-I’m-building-myself-a-Lego-house-on-a-tree-like-this:

There are other areas full of cool Lego displays. One looks like a paleontology museum with giant dinosaurs made of bricks. Another has a huge city model in which you can spend hours exploring different vignettes of life, all brightly illuminated.