What is a folly?

The common meaning is 'an act of foolish-ness'; in archi-tecture, folly is the term for a construction whose purpose is primarily decorative.

Why are these follies?

They serve a primarily deco-rative purpose. Also I think it's more fun. Act of foolishness (positive).

This is a silly thing for you to call it.

I will be the first to admit that. Thanks for reading.