Modular foundation including: • a plurality of prefabricated concrete modules, preferably forming a whole of substantially parallelepipedal general shape, the modules preferably having a thickness between 200 and 300 mm inclusive, this plurality of modules defining: - an upper layer of modules (20; 25) including at least one internal passage opening onto at least its upper and lower faces, - at least one lower layer of modules (30; 35) on which the upper layer at least partially rests, including at least one internal passage opening onto at least one of its sides and onto at least its upper face, the internal passage of said layer communicating at the level of the interface between the upper and lower layers with the internal passage of the upper layer in such a manner as to form at least one global internal passage in the foundation opening onto at least one side and onto at least the upper face of the foundation, the modules of the same layer preferably being assembled to one another laterally, characterized in that at least some of the modules include a vertical cavity on at least two opposite sides and adapted to form with an opposite vertical cavity of an adjacent module a vertical internal passage of greater section, and/or the modules of the lower layer or layers include at least one horizontal cavity on at least two opposite sides and adapted to form with an opposite horizontal cavity of an adjacent module a horizontal internal passage of greater section. • a plurality of prefabricated concrete modules, preferably forming a whole of substantially parallelepipedal general shape, the modules preferably having a thickness between 200 and 300 mm inclusive, this plurality of modules defining: - an upper layer of modules (20; 25) including at least one internal passage opening onto at least its upper and lower faces, - at least one lower layer of modules (30; 35) on which the upper layer at least partially rests, including at least one internal passage opening onto at least one of its sides and onto at least its upper face, the internal passage of said layer communicating at the level of the interface between the upper and lower layers with the internal passage of the upper layer in such a manner as to form at least one global internal passage in the foundation opening onto at least one side and onto at least the upper face of the foundation, the modules of the same layer preferably being assembled to one another laterally, characterized in that at least some of the modules include a vertical cavity on at least two opposite sides and adapted to form with an opposite vertical cavity of an adjacent module a vertical internal passage of greater section, and/or the modules of the lower layer or layers include at least one horizontal cavity on at least two opposite sides and adapted to form with an opposite horizontal cavity of an adjacent module a horizontal internal passage of greater section. - an upper layer of modules (20; 25) including at least one internal passage opening onto at least its upper and lower faces, - at least one lower layer of modules (30; 35) on which the upper layer at least partially rests, including at least one internal passage opening onto at least one of its sides and onto at least its upper face, the internal passage of said layer communicating at the level of the interface between the upper and lower layers with the internal passage of the upper layer in such a manner as to form at least one global internal passage in the foundation opening onto at least one side and onto at least the upper face of the foundation, the modules of the same layer preferably being assembled to one another laterally, characterized in that at least some of the modules include a vertical cavity on at least two opposite sides and adapted to form with an opposite vertical cavity of an adjacent module a vertical internal passage of greater section, and/or the modules of the lower layer or layers include at least one horizontal cavity on at least two opposite sides and adapted to form with an opposite horizontal cavity of an adjacent module a horizontal internal passage of greater section. the modules of the same layer preferably being assembled to one another laterally, characterized in that at least some of the modules include a vertical cavity on at least two opposite sides and adapted to form with an opposite vertical cavity of an adjacent module a vertical internal passage of greater section, and/or the modules of the lower layer or layers include at least one horizontal cavity on at least two opposite sides and adapted to form with an opposite horizontal cavity of an adjacent module a horizontal internal passage of greater section.