A modular construction system based on interconnected universal parts including at least one wall having an electrical wiring circuit built-in into the top end of the wall, electrical lateral connection links built-in into the wall, wall-ceiling electrical connection links built-in into the wall, a water pipeline circuit built-in into the wall, and corresponding fixed lateral water connection links; at least one connector to connect adjacent walls; and at least one roof piece made up of at least one inner side containing the electrical wiring network.