Abstract: A method for the construction, transportation and site installation of a gravity-supported deep-sea lattice structure, characterized by using a dry dock only for constructing the base of the structure, this latter then being completed in protected deep water by successively welding leg portions prefabricated in different construction yards, the welding being done using floating docks, one for each leg, which are provided with lifting and welding equipment and also with automatic raising and liquid ballasting systems, and are connected to said legs in a manner releasable from and slidable along them, to enable the structure under construction to be lowered in a controlled manner after each welding operation, so as to always return it to its initial state and thus make the joining of the leg portions by welding a repetitive operation, the floating docks also being used as pontoons for supporting the structure when, having been made to re-emerge to approximately half its height by means of their said automatic r