ABSTRACT: The increasing demand for sustainable low-strength binding materials, to be used in the conservation of historic masonry structures and as a eco-friendly architectural material, has stimulated the investigation of the properties and performance of clay-based mortars. The study and parameterization of traditional earthen architecture is an increasingly promising research field, in order to assess the sustainability, the durability and the long-term performance of the masonry structures. Several examples of the use of lime-stabilized clay-based binders may be found in the traditional and historic architecture of the Western cultures, besides its widespread use in the traditional architecture of developing countries. In this contribution, three case studies of historic and archaeological Italian masonry structures employing mixtures of lime and soil as binding materials are reported, built in a wide timespan ranging between the VI and the XIII Century A.D.. The study is focused on the chemical and mineralogical characterization of the raw materials employed and in the interpretation of their reaction processes, especially the degree of pozzolanic reaction between lime and the reactive component of the clay fraction. The excellent textural characteristics and ultimate performance of several of the analyzed materials clearly demonstrated their potential, even when employed in temperate climates, opening new perspectives in the field of eco-sustainable binders.