Discusses attempts to achieve complex cultural heritage and environmental protection in harmony with economically necessary developments. In Europe, and in Hungary as well, historic areas have live, organic connections with the existing modern township, though their function and role has considerably changed in time. In many cases, original functions cannot survive, and will be replaced with modern commercial functions to serve and attract visitors to the area. Considerations of possible extensions are discussed, describing various problems to expect, including fulfillment of up-to-date building regulations, hygienic and safety regulations, structural and service engineering problems. Methods on how to achieve solutions to these problems, while keeping authenticity, historic and picturesque values, usage of traditional and replacement materials are discussed. All theoretical considerations are illustrated by case studies of conservational areas and individual buildings.