A modular structure for the construction of buildings, which comprises metal panels to make up load bearing facades and roof covers that include pairs of opposite sides (2, 2'); each metal panel comprising a front plate and a joining system located in each of the sides (2, 2'); wherein the metal panels are secured to each other by coupling the joining systems located in opposite sides (2, 2') of two adjacent metal panels; wherein: - each joining system of the metal panels comprises an anchoring device incorporated into the adjacent sides (2, 2') of the metal panels, and a fastening device that integrally joins the adjacent sides (2, 2') of the metal panels; - the anchoring device comprises a first male-female coupling and a second male-female coupling; - the first male-female coupling is formed by first male elements and first female elements that are located opposite to each other in edges of front plates of the metal panels; wherein said edges are located in correspondence with the sides (2, 2') of the metal panels; - the second male-female coupling is formed by a second male element and a second female element, which (8, 9) are located on main sections of L-shaped protrusions forming part of the metal panels; wherein said L-shaped protrusions are located in correspondence with the opposite sides (2,2') of the metal panels; the modular structure being characterized in that: - the main sections of the L-shaped protrusions comprise end breaks creating channels adjacent to the second male element and second female element of the anchoring device, - the modular structure comprises a system for channelling a fluid that is installed in the front plates of the metal panels, that comprises pairs of flanges integrated into the front plates, the pairs of flanges delimiting grooves in which tubes forming part of a network of pipes fit, so that: - the first male-female coupling provides the modular structure with an outer finishing that is flat and continuous; - the joining of the panels with a double male-female coupling, together with gaskets (19, 20), and the channels provides the modular structure with sealing in facades and roofs; - buckling, overheating due to sun exposure and lack of thermal inertia of the metal panel are avoided in the modular structure by including the reinforcement flanges in the metal panels that enable the inclusion of a network of pipes that irrigate the envelope surface and the load-bearing and coating function of the dwelling, thermal collection and redistribution of the heat may be fulfilled in the modular structure. - each joining system of the metal panels comprises an anchoring device incorporated into the adjacent sides (2, 2') of the metal panels, and a fastening device that integrally joins the adjacent sides (2, 2') of the metal panels; - the anchoring device comprises a first male-female coupling and a second male-female coupling; - the first male-female coupling is formed by first male elements and first female elements that are located opposite to each other in edges of front plates of the metal panels; wherein said edges are located in correspondence with the sides (2, 2') of the metal panels; - the second male-female coupling is formed by a second male element and a second female element, which (8, 9) are located on main sections of L-shaped protrusions forming part of the metal panels; wherein said L-shaped protrusions are located in correspondence with the opposite sides (2,2') of the metal panels; - the main sections of the L-shaped protrusions comprise end breaks creating channels adjacent to the second male element and second female element of the anchoring device, - the modular structure comprises a system for channelling a fluid that is installed in the front plates of the metal panels, that comprises pairs of flanges integrated into the front plates, the pairs of flanges delimiting grooves in which tubes forming part of a network of pipes fit, - the first male-female coupling provides the modular structure with an outer finishing that is flat and continuous; - the joining of the panels with a double male-female coupling, together with gaskets (19, 20), and the channels provides the modular structure with sealing in facades and roofs; - buckling, overheating due to sun exposure and lack of thermal inertia of the metal panel are avoided in the modular structure by including the reinforcement flanges in the metal panels that enable the inclusion of a network of pipes that irrigate the envelope surface and the load-bearing and coating function of the dwelling, thermal collection and redistribution of the heat may be fulfilled in the modular structure.