= Paper =
The technical developpment of the dome has been improved step by step during the islamic period. Political rulers have understood that the knowledges in architecture may serve the spread of Islam. In Iran, the power encouraged different groups of builders that became under the supervision of experts in the art of construction true shools giving birth to different styles and moods in architecture. According to the territorial increase of Islam, teachers and their most skillful students were invited to built monuments through the islamic world. They greatly helped the spread of knowledges. With regard to the problem of the weight of the dome, they contribued to the progressive increase of its stability through more simple forms.