In terms of size, Union Fare certainly resembles a food hall.

The Union Square-adjacent project spans over 50,000 square feet of the decommissioned Barnes & Noble at 6 E. 18th St., comfortably fitting in a classic cocktail bar as well as a more modern tavern-style one devoted to beer, a raw bar, charcuterie station and a cafe-wine bar, all clustered around a main dining room.

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But instead of being a collection of separate venues, Union Fare is about having a choice of ambiance to complement your meal.

“We didn’t divide them up like Eataly or Le District,” says development director Ryan Harris. “Anywhere that there is food production, you can get it in the whole restaurant.”

The overall effect is a space suitable for a lot of occasions, from the tech workers around the corner looking to grab an after-work drink to residents wanting to take their out-of-town parents for a more upscale dinner.

Even with seating there are options, between more casual high tables to barstools (yes, the counters are plenty wide enough for eating on) and traditional four-top tables clustered beneath a constellation of Edison bulbs. Reservations are available — the restaurant officially opens for service tonight — but there are dedicated areas for walk-ins, too.

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The restaurant-wide menu is contemporary American that has undergone a lot of changes as chefs came onboard and were given a chance to pursue passion projects. Harris says former Catch baker Thiago Silva was wooed with the promise of his own bakery (coming later this month next door to the restaurant, along with a food market). He’s also making the restaurant’s desserts as well as the sweet and savory options offered at the grab-and-go cafe, which serves La Colombe coffees (including draft lattes) until 4 p.m., when it turns into a tapas and wine bar.

The main goal of executive chef Yvan Lemoine’s food is “taking dishes that are unhealthy and making them healthy,” explains Harris. That means you’ll still find a steak, flash-fried chicken and mashed potatoes on the menu, but also touches of experimentation with vegetables from the nearby greenmarket. Succulents — the plants for those who forget they have them — are used to thicken sauces, while the raw bar’s cocktail sauce will get its sweetness from beets instead of ketchup.

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“Where a lot of restaurateurs will control everything,” Harris says, “we really let the leash out a little bit because we really wanted these guys to play to their strengths.”