The possession of a significant relic was often the cause for the building - or rebuilding of a church.  With the reception of the relic of the Crown of Thorns, France became the preeminent Christian monarchy.  Louis IX, later canonized during the reign of his grandson Philippe IV, le Bel, built a royal chapel to house the relics. The Sainte-Chapelle of Paris, between 1242 and 1248, became a model for small, exquisite architectural spaces.  The tall stained glass windows compared Louis' reigns with those of Old Testament Kings. The altar was set below a towering shrine where the relics were kept, accessible by spiral staircases on either side. Such prominent displays of relics drew pilgrims like Margery Kempe to sites across Europe.  (Viollet-le-Duc, Architecture, 2:36)   back to "worship"