In Italy, especially in the southern areas, illegal buildings and unauthorized settlements are serious and very old problems that remain unsolved in spite of three building amnesties. As a consequence, local authorities have to face the demolition of an enormous number of buildings, as prescribed by the Italian law. Being possible the execution of only a certain number of demolition orders during a short period due to financial and social reasons, the problem of how to select the buildings arises. This worrying situation had become the object of a special bill giving elements to establish priorities for demolition of illegal buildings. In this work we propose a multicriteria model aimed at giving a rational ranking of buildings on which a demolition order lays on. It is based on TOPSIS method and, given the only database with information on buildings; it is able to provide the competent authority with priority for building work demolitions according to the bill.