This dissertation examines the spatial history of Thailand's so-called second city, Chiang Mai, in order to understand Siam's complex relationship with colonialism and informal empire, and the impact of the formation of modern Siam on the intermediate cities of Thailand. By examining the broader formation of modern Siam through the perspective of Chiang Mai's urban space, this study provides an alternative history that accounts for the contests, conflicts, and collaborations among western forces, particularly the British and Americans, Siamese officials, and local rulers, that transformed the city and the region from an autonomous state to simply Thailand's "north." Founded in 1296 as part of a deep and diverse urban tradition in mainland Southeast Asia, Chiang Mai was the result of several influences. A late-eighteenth century restoration of the city created an urban space that would confront the broad economic and political challenges of western and Siamese intervention in the latter half of the nineteenth century. Economic and political pressures began to reorient Chiang Mai away from inland networks of exchange and towards Siam and British Burma. The shifting balance of power brought British and Siamese interests to the region, while simultaneously transforming the space of Chiang Mai's hinterland from the royal property to a commercial commodity. These changes created a new center that would eventually challenge the validity of the traditional sacro-royal center, when, with the help of several local elites, the offices of the Siamese state effectively "micro-colonized" the old center. While economic and political spaces were integrated into the Siamese state by the early twentieth century, the city itself was "politically disenchanted," as sacred spaces lost their traditional patrons. Escaping Siamese control, sacred spaces remained open to manipulation and mobilization; after a series of dramatic socio-economic crisis, a remarkable monk known as Khruba Siwichai began restoring many of these spaces as a sort of "last stand" of the autonomous Chiang Mai state. His story shows how the sacred space of the north played an important role in shaping the relationship between Chiang Mai and Bangkok, setting up anxieties that persist to the present