Plans made in historical environments, taking harmony between new and old one as the host important concept, create problems ill the approach generally followed by designers. Moreover, the principles of design considered by the designers, and especially facade features and materials, will be illustrated in this paper from an aesthetic perspective. Project principles ill a historical area are changing according to the characteristics of the area and are put forth according to the continuity of the area, location of the building, its formation, its functioning. its historical development, and the level of influence of each building process. Making a project in harmony is still a problem, especially to aesthetic worries. Basic concepts that create aesthetic activity are: order, settlement, harmony, symmetry, incidental details, and dispersion. From these concepts, order is defined as having one element in a building either ill itself or its being distributed in proportion to each other. Settlement is gathering all dimensioned elements with the best suitable way in a building. Harmony is like in a building wholeness, it is the other elements being wholly elegant and balanced. Symmetry is the harmony among the elements of a building and mutual influence on one side of a building to the other side. Incidental details is a view without error composing together with the other parts accepted as fully delightful shaped. Dispersion is the very good distribution of materials and building ground, its usage like using all these concepts ill the present environment_ it is also one of the major problems of forming new buildings ill these environments.