The research topic entitled 'The Architecture of the Opera Houses' focuses on the investigation and classification of different morphological types of Opera theatres according to their construction and functional architectural characteristics. 

The research guidelines are based on the fact that an Opera House is a special building installation intended for theatrical performances that combine prose with music composition in a strict context of musical and theatrical principles. This condition defines the form of the building structure making Opera building a special category of theatres with increased architectural design needs.

Moreover, the fact that the Opera was born in a different social landscape creates reflection on the evolution of the architectural design of the Opera Theatres and especially the relationship of the exterior shell with the individual interior spaces of the opera functions but also how these buildings are either preserved structures or new structures incorporated into the contemporary urban fabric.

Regarding the research process, starting with some general information about the structure and history of the Opera House for the understanding of its role and the design patterns that prevailed, the research work focuses on the study and correlation of 18 building examples of the historical spectrum from the construction of the first building installation of Opera Theatre up to the modern era. The Opera Houses were chosen because of their historical and architectural importance, their timelessness in terms of their operation and finally their popularity. The main objective of the research was the study of the existing bibliographic and historical sources in order to draw conclusions as to the historical context of the creation of Opera Houses, their architectural design and their urban role in the city.