How and why sound to me like slightly different questions and the best one might depend on the answer. "Why is something still standing" could be circumstances

How and why sound to me like slightly different questions and the best one might depend on the answer. "Why is something still standing" could be circumstances related - eg all the other ones got demolished except this one for reason x, or y group of people stepped in to maintain it etc "How is something still standing" sounds more like the method for it standing - eg the structure had some extra cross bracing on the lower level etc Maybe it's just me :)