The paper describes the preload improvement of a newly reclaimed area that is part of the current development of the Barcelona Port. The area will provide the required surface of a new container terminal with a berth length of 1,600 m. The total surface area is 750,000 m2. The improvement affects both the hydraulic fill placed for the reclamation as well as the underlying soft natural ground. Improvement was required for both reducing subsequent settlements and providing an adequate level of stability during construction and quay commissioning. Special attention has been given to the reduction of the liquefaction potential of the hydraulic fill. The degree of improvement has been assessed comparing extensive site investigations performed before and after preloading. CPTu tests have proved especially useful in this regard. An extensive instrumentation scheme was deployed to observe the progress of preloading throughout the whole process. In some areas, preloading was supplemented by the installation of prefabricated vertical drains and by reinforcement using large-diameter gravel columns. The paper describes the ground improvement operations and the field monitoring observations performed during the works.