Are those buildings on that block still in use?
Based on what I know, yes, and the article said ATT's lease would go at least 20 years.
I believe that the buildings house internet and telecommunications hubs for multiple colocation companies due to the history of the buildings being the nerve center going back decades for ATT/BellSouth and, thus, having the connected infrastructure needed for such purposes.
Note that one of the towers has no windows. It was built primarily to house technology, not people.