The paper would look at the principles of architectural composition as analytical distinction of parts, the idea of the structural fragment, the use of open forms and serial repetition, featured in modern and contemporary architecture. Given the possibilities of reinforced concrete structures, light penetrates into the building through the structural frame and shapes the negative-space of the load-bearing form (pattern of light). Moreover, the gap between enclosure and roofing system, the breaks in the walls, the disconnection at the angles in a masonry structure, become a powerful sources of light. The tectonic node shifts from being the robust part of the structure to a hiatus of light. Goals, criteria and methods of analysis of the case studies: In these monumental building, light is the former designing tool. By analyzing the most important historical architectures, the process of spatial design would show the importance of structural form in architecture and it could be used for contemporary approach. The structure bears the loads and creates "machines for capturing the light" at once. Partialized designs have been drawn and re-created with 3d printing technology. An exemplar list of the case studies is the following: - Matching separate structures: Hurva Synagogue L. I. Kahn, Casa della scherma by L. Moretti, Nelson-Atkins Museum by S. Holl. - Gaps between structural series: Kimbell Museum by L. I. Kahn, Padiglione Italia competition entry by F. Venezia, Museum of Architecture in Lisbon by Aires Mateus. - Tectonic hiatus: Hepworth gallery by D. Chipperfield, Palazzo dell’acqua e della luce by Albini and Gardella.