The French Laundry was the first place he worked at, and it's northern California. Then he worked at Ever, the Chicago restaurant owned by Chef Terry where Richie staged last season. Chef Terry then sent him to Copenhagen to learn at Noma, and I'm guessing whenever he came back from Copenhagen was around the time of Fishes (S2E6). After his disastrous visit home that Christmas, he decided to take up his cousin Michelle's offer to come stay with her in New York and get into the restaurant scene there. The restaurant they show him working at in NYC is Daniel, but previously his backstory was that he worked at Eleven Madison Park in NYC, so I'm a little unclear about that. I think he was in NYC for more than 4 years - basically from right after the Christmas from hell until he came back home after Mikey's suicide a few years later. Sydney ate "the best meal she ever had" at Daniel in New York City - the scene with her eating Carmy's meal was filmed in the actual restaurant.
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