The Baltimore shelter is a location that appeared in Season 9 of AMC's The Walking Dead. It was a warehouse that was turned into an emergency shelter that survivors in Baltimore sought refuge in as the apocalypse unfolded.
Nothing is known about this location before the apocalypse aside that it was a warehouse.
As part of Alpha's and Lydia's backstory it is shown that during the early days of the apocalypse they were held up at the basement of a warehouse in Baltimore alongside Alpha's husband and Lydia's father Frank as well as with some other survivors that include Matias, Lamar, Rose, Amanda, and Cyrus. After some time some of the survivors had left the compound in order to find help but never returned. One day, Matias paniced as the undead started to invade the warehouse, however, Alpha quickly killed him so as not to give up their location. During the night, as Matias's brain hadn't been destroyed, he reanimates and starts attacking the rest of the survivors in the shelter. During the chaos Alpha kills her husband Frank and alongside Lydia leaves the shelter and let the remaining survivors be devoured by the undead.