Permanent exhibitions may have a lifespan of then years, sometimes more, and tend to be located in museums or galleries. This planning stage of such exhibitions can spread over several years. Large budgets and maintenance programmes are necessary to keep them in pristine condition, and to support areas within the exhibition that have to be reworked due to changes in science or popular thinking. The designer’s role, however, normally ends when the completed design is ‘handed over’ to the client.