A World War II-era alert billboard outside the former K-25 uranium-enrichment plant, now a history… https://www.rawpixel.com/image/8061869/photo-image-face-plant-personFree Image from public domain licenseRetro Billboard in Oak Ridge https://www.rawpixel.com/image/10170444/retro-billboard-oak-ridgeView licenseRetro Billboard in Oak Ridge https://www.rawpixel.com/image/10172263/retro-billboard-oak-ridgeView licenseRetro Billboard in Oak Ridge https://www.rawpixel.com/image/10172298/retro-billboard-oak-ridgeView licenseRetro Billboard in Oak Ridge https://www.rawpixel.com/image/10170488/retro-billboard-oak-ridgeView license