The original Shake Shack was actually an art installation

Today, “fine casual” fast-food chain Shake Shack went public.

Some may know the company has its roots as a burger stand in Manhattan’s Madison Square Park.

But many may not know that its original incarnation was even more humble: Before it even became a shack, it was a hot dog cart.

According to its IPO filing, Shake Shack was born in 2001 during a Manhattan public art exhibit called “I <3 Taxi". The installation was conceived by Thai artist Navin Rawanchaikul, who turns taxis and taxi culture into works of art (though it turns out NYC cabs hated the idea). Here is what the pre-Shake Shack hot dog cart looked like before its paint was removed.

“A decorated hotdog stand was set up nearby for leisurely perusal,” Rawanchaikul’s website says.

What it doesn’t mention was that the cart was actually run by megachef Danny Meyer’s Union Square Hospitality Group.

“The hot dog cart was so popular–with epic lines to match–that all three major TV networks and CNN covered it in their nightly news reports,” the company says in its filing. The New York Times even sent their restaurant critic to write a review.

The cart stuck around for another couple of years before Meyer decided it needed to become more substantial, and Shake Shack was born.

Today, there are 63 Shake Shack locations around the world.

Rob covers business, economics and the environment for Fusion. He previously worked at Business Insider. He grew up in Chicago.