WITCH MARKS

Apotropaic (or witch marks) were common forms of protection for your house. These carved designs are usually found by doorways, windows, fireplaces or anywhere that evil spirits might enter the home. The marks can take various forms but most commonly you will find a daisy pattern. It was thought that once the evil spirit became entangled within the circles it would never escape. It wasn't just houses that used this type of protection from evil, many religious buidings also have them. The second photo, showing a less common pattern, was found at Bath Abbey a few years ago during renovation work. They're commonly found in buildings between the medieval period through to the 19th century, but many date from much earlier.
The use of these magical symbols was commonplace at that time, along with other methods to protect the home from evil. Even today, it's not that unusual for various items to be found hidden within a building during renovation work (within walls, under the floor, beneath a hearth stone etc). Recorded items from various buildings include shoes, dolls, cats, witch bottles (containing pins, human hair etc), and even a horse's skull.