The latter half of the nineteenth century saw an unprecedented increase in technology. The use of new materials such as iron and glass architecture has accompanied many changes. These changes have occurred in the social, economic and cultural fields, which changed the aesthetic values of that era. Modern art designer tried to do that. It is done to bridge the gap between aesthetic value and new technology, where the technology was hidden behind the art. (Barbara W. 2015 (11)(. Art Nouveau designers' senior who incorporated designs decorative iron as a new architecture designed is Victor Horta (1861- 1947).He is one of the founders of modern art. He was the first major act of his work carries the thought and principles of modern art is Hotel Tassel ((1892-1893. In Brussels, it has also appeared this trend in Paris. Patrons designer are Hector Guimard (1867-1942). The important his work that still pays for Art Nouveau entrances Metropolitan "Metropolitain" or the Paris Metro. 1899-1904 and he has 141 input. (Hector G.2015 (19)). The research problem is despite the passage of many years. Most novice designers tend to automatically apply the principles of modern art. Hence it must be need to understand the design and construction bases of the decorative iron work in the Art Nouveau architecture. The research Objectives: The research aims to study the use of decorative iron that employed by art designers of modern architecture (stairs, balconies, doors, ...... ). This is developing a vision for the integration of conceptual foundations of iron decorative design with architecture. based on the Art Nouveau style. creating curriculum method to teach the foundations of. It based on inspiration from nature depending on the style of art talk. The most important results, the application of technological techniques, with architecture decorative iron, when the design of Modern Art for Architecture, given the high aesthetic value with the luxury and originality. As well as their applicability to all classes (upper-middle-minimum), provide technology value, economic, with high quality.