This dissertation theorizes the notion of Siamese diorama and its techniques of controlling as a political and aesthetic metaphor of Thai national imaginary. Similar to Jeremy Bentham's panopticon, which is an architecture of control, the diorama controlled its audience by producing false perspectives, and by compressing and miniaturizing nature. The diorama then becomes a machine producing nature-like effects. I demonstrate that the Siamese diorama is an inbuilt system of representation that envisions the national imaginary for Thai subjects. It suggests that the Siamese diorama uproots and confines its audience within a linear narrative of national history. The Siamese diorama also highlights hierarchical structure of culture that has been rendered in international art exhibitions, where contemporary Thai art is situated in response to both a Thai and a Western gaze. My dissertation demonstrates that contemporary Thai artists create a possibility of challenging, criticizing, and expanding the field of the national imaginary. For example, while Chalermchai Kositpipat's works are celebrated to represent official Thai-Lanna and Buddhist culture, Montien Boonma's artworks open up a possibility to reconfigure a space of Buddhist art in which he used local materials and deepened his interrogation of traditional Thai art. As an overseas Thai artist, Rirkrit Tiravanija's use of Phad Thai in contemporary art demonstrates a fluidity of Thai culture through his improvisation of cooking Thai food. Navin Rawanchaikul's Fly With Me to Another World, in which he installs the individual history of a Thai national artist Inson Wongsam in Hariphunchai National Museum, enhances a possibility to decolonize time in the Siamese diorama. Lastly, Araya Rasdjarmrearnsook's use of cadavers provokes and offers a reading of Thai female landscape calling for disrupting Thai national imaginary. The rise of contemporary Thai art is intertwined with the rise of international Asian art festivals, which is a part of the internationalization of Asian art. The emergence of contemporary Thai art is thus a negotiation in the art world's hierarchical structure as well as in its national imaginary.