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In honor of Shake Shack’s 100th restaurant, the burger joint will be giving away free sandwiches to the first 100 customers at most of its worldwide eateries.

As the latest location opens at the Boston Seaport on Tuesday, D.C. residents can line up the three locations in the city. Up for grabs is a free single ShackBurger or a burger of equal or lesser value. The promotion will run from 10:30 a.m. until noon.

The company was born from a hot dog cart in Madison Square Park run by restaurateur Danny Meyer. It became official in July 2004 with a permanent kiosk in the park.

When the chain’s first D.C. location hit Dupont Circle in 2011, one Washington Post headline read “Shake Shack finally puts D.C. on the map” (followed by the first sentence “Well, not quite.”) Whether or not that’s true, the joint did expand the city’s meat and veggie burgers options. Locations have since popped up in Nationals Park, Penn Quarter, and Union Station (in addition to a couple spots in Northern Va. and a forthcoming outpost elsewhere in Navy Yard.)

All of these locations, except Nats Park, are offering the deal.