A roofless, three-sided outbuilding stood in the backyard of a future River City Habitat for Humanity home.
As renovations to the 1920s-built property in the 800 block of Clark Avenue proceeded, the time came to raze the structure - builders thought there might be salvage materials.
What they discovered were about 100 decommissioned Civil War veteran markers.
"It was an interesting combination of curiosity and fear when we started uncovering these tombstones," said Habitat board president Mark Johnson.