points up, and it's called a lintel.

Not sure about the superstition being based around iron, as it's been a protection against witches for considerably longer than there have been horseshoes.

There was a huge Shire horse by the name of Prince, lived at the bottom of my road when I was growing up. He was a massive beast, and won many prizes. Each shoe had to be specially made as it contained twice the amount of metal than the standard shoe. It measured nearly 14 inches across, if he lost one, you really WERE lucky to pick it up, they weighed what felt like a ton!

LTS