"The Tower" or sometimes "The Lightning Struck Tower" are modern titles for La Maison Dieu, which translates as Hospital or Foundation (a funded establishment). So really, the "crown" is the head, and the idea is that what's below is permanent, and what's above is transient. Basically, our vision is the reality, and external forces are distractions. The key may be the answer to: Why is a raven like a writing desk?