I have always loved Celtic crosses.
There is just something so appealing to me about them, whether they are the massive, intricately carved stones that are used as a grave marker, or a delicate filigree pendant worn around the neck. I suppose it is because of their beauty, and because I am half Irish.
Although essentially all the same shape, the cross with the circle around it, they are all so different from one another, with the knot work, spirals, key patterns, meandering patterns, and sometimes even human or animal figures. Some are very crude and primitive, while others are overly ornate. The wide variation of styles, coupled with their rich history and how they are interpreted, are the reason Celtic crosses are very often a popular choice for both jewelry and tattoos.
While browsing for photos of Celtic crosses, I came across this wonderful website which goes into detail about the history and symbolism of Celtic crosses, as well as Celtic knotwork in general.
Here are some other examples of Celtic crosses: