Amazon’s revolutionary “grab-and-go” grocery store is now open in Chicago, marking its first expansion of thecashier-less storesoutside of the company’s home city of Seattle, theChicago Tribune reports.

Rumors that Amazon may introduce its stores to new markets started swirling after job ads indicating the company was looking for people to manage the new Amazon Go stores in Chicago and San Francisco were discovered byThe Seattle Times. Amazon later confirmed to the Times that it was indeed planning to open Go stores in Chicago and San Francisco, but declined to offer any dates. Now, the Chicago store is open for business.

Amazon didn’t do a great job keeping its plans under wraps. The company had a building permit for the construction of an “Amazon store” in Chicago’s Loop district, according to real-estate trackerCurbed. It was also discovered that Amazon has been planning to open up a store near San Francisco’s Union Square, as reported by theSan Francisco Chronicle.

The Amazon Go technology tracks shoppers as they make their way around the store. All they need to do is scan their Go app once when they enter, and, well, that’s it. The store uses sensors, cameras, and artificial intelligence technology to track what you’re putting into your bag as you move about the store. It’s even smart enough to notice when you take an item out of your bag and put it back on the shelf, should you change your mind while you’re making your way around.

The company spent the whole of 2017 testing the technology with employees, using the trialto refine the systembefore the official opening at the start of this year. It has since openedseveral other locations around Seattle.

For visitors to the store, it’s a one-of-a-kind shopping experience, with some even wondering if they might bearrested for shopliftingwhen leaving, without any apparent payment transaction having taken place. But it has. Check your Go app and you’ll see how Amazon has logged everything in your bag and automatically charged your account.

Interested to know what it’s like to shop at an Amazon Go store? Digital Trends’ Jenny McGrath was one of the first people to shop at the Seattle store, so take a moment to find outhow it went for her.

Updated on September 17: Amazon Go opens in Chicago.