The old-photo blog Shorpy has a post up this morning showing a 1914 photograph of a municipal Bat Roost in San Antonio, Texas. It took me a few moments to notice the man standing on one of the cross-timbers of the structure and to realize just how large the thing is. We don't see timbers that large much anymore. Certainly not in utility construction. Have a look also at the close-up of the posted explanation and anti bat-slaughter ordinance.
Update: According to Dave, over at Shorpy, the supports that I took for timbers are in fact poured concrete. I'm disappointed to have been wrong, but still impressed at the size of the Bat Roost.