The primary focus of this research is to investigate the historical evolution of urban planning in California and its current urban landscape. With the increasing development of highways and convenience for car owners, the city has become more and more dangerous and inconvenient for bikers and pedestrians. People constantly take long detours and risk their safety during a walk or a bike ride, and the increasing pollution consistently harms people’s respiratory health. So the aim of this project is to propose an alternative transit reality for Californians, envisioning a more significant impact not only on urban planning but also on their lifestyles through a 15-minute city plan. Guided by four principles: Ecology, Proximity, Solidarity, and Participation, to create a green and sustainable city, advocate the idea of living with reduced distance to other activities, creating links between people, and actively involving citizens in the transformation of their neighborhood.