Not much is known about the estate before or when the outbreak started, other than it was a residential community located just outside Richmond, Virginia, approximately 530 miles northeast of Atlanta, and where Noah lived along with his family.
Not much is known about the estate other than, according to Noah, there were 20 people in the community, including himself, his father, mother, and little brothers. He and his father, upon embarking on a search mission for Noah's missing uncle, were ambushed by the Grady Memorial Hospital group when arriving in Atlanta. Noah was taken, while his father was left behind to die.
At some point following Noah and his father's departure, the community was pillaged by a hostile group called the Wolves, who killed all the remaining inhabitants.
Noah took Rick Grimes's group to the community, in a hope to find a new safe place to rebuild their life. However upon reaching the place, they found the place has been overran and lost to the walkers. The fences are destroyed, and some of the buildings were burned. Noah was devastated upon learning the truth about his home, and his family whom he found dead in their house. One of his twin brothers reanimated as a walker and bit Tyreese on the arm, infecting him, which led him to his death hours later.
The name of Shirewilt Estates is a reference to Wiltshire Estates, a semi-prominent location in the early issues of the comics and that was shown in Season 2 of the show, though it was never named onscreen.
A group called the Wolves attacked Shirewilt, as the words are spray-painted onto a stack of bricks, "WOLVES NOT FAR", along with several walker torsos nearby which have a W carved into their forehead. The homes in Shirewilt are burned, likely with Molotov cocktails, and the citizens appear to have been killed and mutilated. Noah's mother's corpse had a large gash in her head. The sliced walker bodies, tire marks, and broken wall from behind Shirewilt seem to be a nod to The Wolves as well.
It was confirmed by Greg Nicotero on Talking Dead that humans were responsible for Shirewilt's destruction and not walkers.
Shirewilt Estates is actually filmed at Foreston Place in Peachtree City, Georgia.