Much more than a formal model, landscape is important to architecture and urbanism as a model of process. Landscapes cannot be designed and controlled to the degree that architecture is; instead, landscapes, like cities, are loosely structured frameworks that grow and change over time. Landscapes are immersive environments, diagrams subject to partial control. Time is a fundamental variable in landscape work. Today, landscape architects are embracing change and designing landscapes that anticipate a succession of states: a choreography of changing plant regimes, shifting spatial characters and new uses over time. Working with a precise spatial framework, the designer creates the conditions under which distinct and perhaps unanticipated spatial characteristics may emerge from the interplay between designed elements and the indeterminate unfolding life of the site.