The aim of this paper is to show the significance and theoretical aspects of 3D-reconstructions of badly preserved ancient architectural masterpieces both for architectural theory and modern architectural practice. Contemporary interpretation of classical architecture is mainly based on foundation which was created by architectural and art historians in XVIII-XIX centuries. However contemporary architectural history rested on the newest progress of archaeology gives us a lot of new information about badly preserved antique architectural masterpieces. 3D-reconstructions of such monuments based on the modern computer technologies have to increase our conception of ancient architecture and discover the new stratum of Greek and Roman architectural monuments both for architects and for the wide public. In the Moscow Institute of Architecture the creation of such reconstructions is a part of educational process and scientific research. The paper is accompanied with author's reconstructions of two monuments: late Roman palace at Nag-el-Hagar and the temple of the Roman imperial cult at Luxor and also with several examples of 3D-reconstructions made by foreign scholars.