Mega Events are considered to be important impetuses for the regeneration of their host cities as much as for the economic development of their countries. This study examines a number of events planned to take place in Istanbul since the mid-1930s. Although the projects studied here never progressed beyond the planning stages, they have been understood as an important influence upon urban development. Henri Prost, who oversaw the planning of Istanbul from 1936 to 1951, first introduced the idea that the Olympic Games and international exposition might serve as structural tools for urban transformation and development. Organizing the Olympics has remained an aspiration for Istanbul since then. At the turn of the twenty-first century, Istanbul applied officially to host this Mega Event. This paper analyzes the ways in which plans for these Mega Events impacted upon urban development in Istanbul.