The stone crosses in Scotland and Ireland are a continuation of a long tradition of Celtic standing stone monoliths such as Stone Henge. This tradition developed into stone crosses with the introduction of Christianity. Most date from the 9th to 10th century. All parts of the Celtic Cross have symbolic meanings. The most recognizable being the outer ring representing heaven. Knotwork represents eternal life. The Maze pattern is the path of spiritual growth. Spirals also symbolize spiritual growth.