Union Square Greenmarket is a great place to shop for super-fresh fruit, vegetables, meats, cheese, breads, flowers, plants and a lot else. It's what "real" New Yorkers do and is also fun for out of towners who ogle the plethora of deliciousness spread before them as well as the hare krishna guys, babies and dogs with owners.
When you've had your fill of shopping for food, it's nice to kick back with a drink or a meal and at Pavilion you don't have to walk far--it's right in Union Square Park at the north end.
In warm weather there is a very pleasant outdoor space with green-and-white wicker chairs and bold, orange umbrellas, especially nice if you can sit so you don't see Petco and other shops directly across the street. The elegant old, building with a classical arch, has a long flight of steps in front and greenery everywhere, simulating a tropical escape. It's pretty and romantic if that's your inclination. Inside, is a long bar and decently spaced tables although in the evening the bar is jammed so the noise level gets close to terrible. At lunch it's fine. There are heat lamps to keep the open air space comfortable although taking a sweater or wrap is a good idea.
Servers are incredibly friendly yet a tad casual--it can take a long time for an order to appear or a check presented.
Menu items are "market-driven," very fresh and simple. The tomato and goat cheese tart starter is a good bet as are the mushroom crostini or the pretty, apricot-colored tomato soup with goat cheese and farro. Sandwiches, that come with a mesclun salad or fries, include a croque monsieur, organic chicken and a tuna steak with wasabi coleslaw that's short on the wasabi kick, probably to please the fairly unsophisticated crowd. There are oysters, shrimp and various seafood crudos, as well as a host of pretty, generously portioned salads like the organic kale Caesar, Greek, or beet and frisee. An entrée can be a hanger steak with fingerling potatoes; short rib and broccoli rabe lasagna (which many find a little weird as a combo) or mussels with more of those pretty crispy fries. The dinner menu is pretty similar with more emphasis on the market veggies. In general, the food is on the light side which may leave you wanting dessert ($8) such as the chocolate beet cake (the beets are the sorbet; the entity much better than it sounds; devils cake, a pistachio and raspberry concoction and the summer version of cheesecake incorporating basil, citrus 'salad' and lemon curd.
Very good cocktails are available as are draft and bottled beers; wines by bottle or glass, gluten-free cider (this is NY where anything is possible) and lots of tea and coffee options. Lunch begins at 10:30 AM and runs until 5 PM; dinner takes over at five until midnight and brunch, a particularly enjoyable meal here, is 11:30-5 PM weekends. Restrooms are unisex. All major credit cards OK. The atmosphere is so lovely I always end up enjoying my meal despite the slightly lackluster food.