The McAllen Public Library in McAllen, Texas, is the size of 2.5 football fields — the largest single-story library in the United States. But in its former life, its size wasn’t all that unusual. That’s because the McAllen library used to be a Walmart.

The company that redesigned the building, Meyer, Scherer & Rockcastle, Ltd., started by removing the old ceiling and existing interior walls. The cavernous space allowed plenty of room for an auditorium, computers lab, classrooms and meeting rooms, and adult and teen reading lounges — not to mention hundreds of thousands of books.

The best part: Library registration jumped 23 percent after the new building opened. Sure, some of those people probably wandered in looking for a gun and 200 diapers, and just took a while to figure out what was going on. But a lot of them just wanted to make use of a beautiful new public space.