Unknown to most patrons of the Lake Street McDonald’s in Chicago’s village of Maywood, there is a memorial to the Underground Railroad right in the parking lot of the fast food chain.

Along the Des Plaines River, at the northeast corner of the McD parking lot, a repurposed train track split in two is on display. In between the two tracks, there sits a plaque which honors the work of Harriet Tubman and the Underground Railroad in “the escape from the chains of slavery,” symbolized by a pair of broken shackles mounted next to the plaque.

Why would an Underground Railroad monument be placed so close to the Golden Arches? According to Northica Stone, the founder of the West Town Museum of Cultural History, the McDonald’s stands on the former site of the Ten Mile Freedom House, which, according to her research, was once a safe haven for runaway slaves fleeing the antebellum South along the Des Plaines River. For Stone, this is the missing piece to Maywood’s Underground Railroad puzzle.

The Ten Mile Freedom House was once a resting place for settlers bringing their crops to Chicago—so named because stops were spread 10 miles apart—but was used by abolitionists during the mid-19th Century to shelter escaped slaves. The house was torn down in 1927, but there’s no doubt that its vital legacy lives on today.