We propose an approach to generating virtual cities that vary dynamically over time, focusing on the layout of artificial elements such as building, roads, and traffic lights. We first define an environment vector as the amount of features reflecting economic and functional activities of city's residents in each block surrounded by roads. Our method generates virtual cities by deleting and locating buildings from two points of view: building layouts using environment vectors, which can represent features, themselves to generate cityscapes, and time-varying using changes of vectors to vary cityscapes. We introduce three modules of our city model briefly, and describe how our system relocates buildings in each block. In addition, we demonstrate that our method can represent features and generate various cityscapes that vary over time.