Impenetrable restaurants are nothing new. History tells us that the tougher the table is to reserve, the more mystical its allure. It’s been that way from the 1960s heyday of places like the Colony Club—when Sinatra and Capote vied for the same corner seat—to the latter-day opening of hot new upstarts, booked weeks out before the paper is peeled from the windows. But in recent years, the quest to keep current in the food world has taken a more masochistic turn.

As restaurant-going replaces baseball as America’s favorite pastime, the country’s most ambitious chefs are now breaking away from the classic three-course form. These days some of the nation’s most exciting food is coming out of underground eateries, restaurants-within-restaurants, peripatetic supper clubs, and pop-ups—nomadic upstarts that have made moving targets of the country’s most desirable dinner tables.

From secret chef’s counters to invitation-only omakases, we take a look at under-the-radar dining experiences that are worth tracking down.