The first consists of defining perimeters on Land Occupancy Maps within which any construction can be prohibited or severely restricted so that an "archaeological reserve" can be created. This procedure, which is rarely put into action, is necessary when a site has major archaeological potential. The site can also benefit from protection as a historic monument: this second procedure is applied when the site poses preservation and/or development problems. These questions fall more particularly within the province of the Conservation Régionale des monuments historiques.

A sector of the Plaine de Saint-Romain-en-Gal, where one of Ancient Vienne’s districts is situated, comes under this type of protection. Abandoned at the end of the Roman era, this sector has, on the whole, been spared by new construction since then. These exceptional conditions mean that a fairly well preserved, homogeneous sample of the ancient city can be kept for the future and part of it can be opened to the public. The excavations underway at the site archéologique de Saint-Romain-en-Gal are programmed. They are systematically followed by consolidation and development of the remains.

In the greatest number of cases, where, a priori, there are no construction bans, other regulatory measures can be taken in order to forestall any blind destruction. The Service Régional de l’Archéologie can define sensitive zones which are entered on the Land Occupancy Map. Within the boundaries of these zones all urban planning documents are submitted to the Service Régional de l’Archéologie for an opinion. The Department can require preservation measures to be taken if it considers that the remains can be threatened by the projects.