Horse shoe to the Door?

I'm not really superstitious but I hate to see a horseshoe upsidedown. It's got to keep the luck in.

In England (and generally in Europe) a horseshoe nailed to or above the main door of a dwelling or a stable specifically to prevent witches from entering. Farmers sometimes believed that witches would 'borrow' horses during the night and ride them hard so that, in the morning, the horse was found to be weak and sweating (this was probably actually because the horse had a fever). There are several cases noted by 19th Century collectors of British folklore where people suspected that they were put under a spell by a local witch and sought to prevent or annul the spell by nailing a horseshoe to the door. The origin of this superstition is debated. Some think that it came from the worship of the moon, others have said that it was because the image of a saint with a gilded halo was often painted on doors and that, over time, the image weathered away leaving just the gold, horseshoe-shaped halo. This latter is really rather unlikely, since the 'horseshoe' would then be with the open end downwards and the 'luck' or 'magic' would be supposed to fall out! The fact that smiths have long been thought of as magicians and healers and possessed of special powers is a much more likely explanation for the use of horseshoes as a prevention against evil.

I knew a little bit about the Horse shoe nailed to hold good luck but that was the limit. I learned even more after reading this post and its comments!! :)