The concepts of space and time have dramatically changed with the development of modern sciences, such as geometry, physics, and astronomy. This radical shift also changes every aspect of our perspectives, including those on urban space and urban planning. With a brief introduction to the evolution of geometry, this article discusses the development of the way we think about and evaluate urban space. Such development is divided into two phases: homogeneous urban space and generalized non-Euclidean urban space, each with corresponding patterns of urban planning. Some key issues in the non-Euclidean pattern of planning are then explored intensively, such as varied measurements of urban land, geodesics in the city, and urban planning in spacetime. While emphasizing the way of thinking in urban planning process, this article provides some proposals that differ from those related to absolute space.