Not many things carry such legend and superstition like an Iron Horseshoe.
When hung above the door with the arms pointing down towards the ground it creates an extremely powerful protective energy, preventing anything (physical or spiritual) that means you harm, from passing over the threshold of your house.
Similarly, if placed with the arms pointing up it creates a bowl-like shape which is said to attract and contain wealth and riches, bringing money and prosperity into the home or business place.
Not all horseshoes work in this respect, you can often find ornamental horseshoes in garden stores or furniture stores, more often than not these are made from steel and have never been used. These ornamental horseshoes are merely decorative and do not carry the same magical benefits as a real Iron Horseshoe.