Blast from the past: At the request of J.W. Marriott Jr., Anthem in the Marriott Marquis Washington sells the Mighty Mo burger, once a Hot Shoppes staple, served with a side of fried onion rings. (Yue Wu/The Washington Post)

When he was mulling what to offer at Anthem, the casual American restaurant on the ground floor of the behemoth Marriott Marquis Washington, executive chef Matthew Morrison wanted to steer clear of the expected hotel fare. Sure, he needed to appeal to guests staying upstairs: There had to be a burger. But Morrison says he also hoped to give patrons a sense of what’s local.

Enter a twist on chicken and waffles, designed as a sandwich. Customers of the restaurant, a modern diner that recalls the Marriott Hot Shoppes of yesteryear with a nine-seat counter looking into an open kitchen, also can catch rockfish. Sauteed to a gentle crisp and bedded on corn risotto, the entree zings with a garnish of pickled vegetables.

Chicken soup is an early top seller. One reason for that might be its tiny ravioli filled with Gruyère, a pleasant change of pace from the typical long noodles. Sweetened with minced carrots and abundant with chicken, the steaming soup is an elegant version of the diner staple. Thyme and oregano, plucked from an herb garden on the hotel’s 10th floor, help season the crowd-pleaser.

The chef’s most important client had a simple request: Make the Mighty Mo available, instructed no less than J.W. Marriott Jr., the hotel company’s executive chairman and chairman of the board. One of a handful of Hot Shoppes classics, the double-decker hamburger is presented with Mighty Mo sauce in a sesame seed bun alongside onion rings that smack of a freezer product. The recipe for the condiment — ketchup, lemon, chili sauce, mayonnaise — comes straight from the hotel archives and stands the test of time.

Trendy kale makes a couple of appearances, in a bountiful salad with strawberries and toasted almonds and as oven-baked chips flavored with soy sauce and sesame oil. The latter, dusted with Parmesan, make for a chewy and harsh snack.

The hotel has done an admirable job of creating a space that nods to the past while staying in the present. The room is open and curvy, dressed with stippled white walls and lights and fabrics in shades of red, cream and orange. Like so many new restaurants, it’s also clamorous at peak hours.

“Anthem” makes sense to anyone walking through the hotel’s airy white lobby. The expanse reveals a patriotic theme, most obviously in the 56-foot-tall stainless-steel sculpture called “Birth of the American Flag” by Baltimore artist Rodney Carroll.

Since it opened in May, along with a sports bar and lounge, Anthem has served breakfast and lunch. Dinner hours are likely to be added down the road, says Morrison, who came to the Marriott’s 4,000th hotel from the Ritz-Carlton in Tysons Corner.

The chef’s initial efforts suggest that, come the night, more than hotel visitors will be showing up for a bite to eat.

901 Massachusetts Ave. NW. 202-824-9200. Lunch appetizers, $3 to $12; main courses, $16 to $22.