The first-ever K-25 reunion brought in approximately 650 retirees and others to the site of what was once the world's largest building. The event was held from noon to 3 p.m. April 27 outside the K-25 History Center on Enrichment Street. Former workers from the Manhattan Project until now, along with friends and guests, showed up. The site has been known by many names in its 80-year history, but for those who worked there, and others in East Tennessee, it will always be known as "K-25," its Manhattan Project code name. See more photos and video from the event at oakridger.com.