Started in 1976 by Ph. Bechelen, air survey in the « département de l'Eure (France) » is now being carried out by v. and J.-N. Le Borgne and G. Dumondelle (who study the Western area), P. Eudier and A. Étienne (in the Eastern area), within the framework of the association Archéo 27 (number of the departement). Whenever a site is located, a systematic investigation is made (former and recent cadastres, field controls, former publications). Several hundred sites have already been reported. They reveal great differences according to the type of vegetation, the results often being negative in the bocage as opposed to some rich plateaux and valleys. Other differences appear according to the area under study : in the area studied North of the Seine river, few ditched structures are to be found. A first typological study of the enclosures located in the area that stretches over a quarter of the county has been made, after the studies by R. Whimster and by L. Langouet and M.- Y. Daire. As far as the gallo-roman remains are concerned, in spite of some findings in the departement, an overall study is still premature. Only the site of « Le Vieil-Évreux » is investigateci for a cartographic survey. As for Medieval and post-Medieval times, aerial surveying brings aciditional information about sites that are already known as well as revealing new ones.