NELSONVILLE, Ohio (AP) — The ongoing theft of historic bricks has frustrated officials in a small Ohio city who spent a lot of time tracking down the bricks for downtown sidewalks.

At least 50 so-called Nelsonville Star Bricks have been taken since early January, said Nelsonville city manager Chuck Barga. The bricks are a legacy of the city’s brick-making history, and won first prize at the 1904 World’s Fair in St. Louis. Each has a star imprinted in its center.

At least three brick producers once called Nelsonville home thanks to large clay deposits in the area.

Though millions of Star Bricks were manufactured between the late 1800s and about 1920, the bricks are no longer made, which makes the thefts all the more frustrating, Barga told The Columbus Dispatch.

The city tracked down the bricks for a renovation of Nelsonville’s downtown a couple of years ago.