The aim of this paper is to understand what the chemical influence of the concrete on the corrosion form present is, on rebars embedded for tens or hundreds years. Therefore, metal/concrete interface of samples coming from two French Historical Monuments has been characterized: ‘Bourse du Travail’, Bordeaux, 80 years old and ‘Maison du Brésil de la Cité Internationale de Paris’, 50 years old. The collected samples have been observed on transverse section in order to observe the whole corrosion system (metal/corrosion products/concrete). Morphology, elementary composition and structure have been studied with complementary analytical approaches (optical microscope, scanning electron microscope coupled to energy dispersive spectroscopy and Raman microspectroscopy). Thus, a fine description of the corrosion scales formed on the metallic rebars can be schematized. On the basis of these results, mechanisms hypotheses are proposed in the discussion.