Before the apocalypse occurred, this building was a senior citizen resting home and was the home of Abuela and Mr. Gilbert. They were under the care of a nurse named Felipe as well as other medical staff. Guillermo also worked at the building as a custodian. Once the outbreak began, most of the medical staff fled the building to meet up with family or to attempt to evacuate Atlanta, leaving the senior residents to fend for themselves. Guillermo, Felipe, and a few others decided to stay behind and help them.
When Rick Grimes and his group clash with members of the Vatos gang over the bag of guns, resulting in Glenn Rhee being kidnapped, Rick demands that Miguel, who was also captured by Daryl Dixon, to guide them to the Vatos base camp. Miguel leads his captors to the nursing home, where several armed men emerge. The building has a loading dock filled with equipment and many vehicles, along with dozens of men of the Vatos gang that are working on the automobiles. Guillermo and Felipe nearly are involved in a gunfight with Rick and his group until it is revealed that they vowed to protect the helpless seniors along with the help of fellow gang members, who dream of one day repairing enough cars to evacuate every last senior out of the city.
The nursing home was left alone and Rick donated several guns and ammo to the gang so they could continue to protect the home, and its people, from walkers and other threats.
It is unknown whether or not the Vatos crew were aware of the true nature of a walker's resurrection outside of being bitten. As they are inside a nursing home, however, it can be assumed they knew or would have soon learned.
In deleted scenes from the first episode of Season 2, "What Lies Ahead", Rick's group returns to the Atlanta Nursing Home to find shelter again. As they arrive to find it abandoned, they discover the elderly inhabitants lying dead on the ground, with gunshot wounds to the head; "execution style", according to Daryl. There are no traces of the Vatos gang, save for a few bodies of the thugs in the courtyard when Rick and the survivors encounter the compound.