The Empress decided to extend the exemptions from customs duties to the whole city,[1] which attracted many people from different countries and all walks of life (Italians, Serbians, Slovenians, Croats, Jews and Greeks): for them a law was passed, the "Editto di tolleranza", which provided for the freedom of worship, the possibility to negotiate freely and to own goods.In 1857 the Südbahn (Southern) Railway line became operational along the northeastern route: Trieste, Postojna, Ljubljana, Graz, Vienna, with further links to Budapest and the Balkans.The fourth period, between 1924 and 1936, is characterised by the realisation of major public works, which were to complete the sea infrastructures, the port equipment on piers V and VI, the Silo, the Stazione Marittima (the passenger station), and the Idroscalo (the air harbour).After reconstructing the buildings damaged by the bombings of the Second World War, an innovative port reorganisation was started in line with the needs of the containerisation and the new transport systems.Granted in 1719 by the Habsburg monarchy and restricted in 1891, this special status has been confirmed by subsequent peace treaties, by the European Community and by the Italian Parliament.A series of two-flue Lancashire boilers with a 2.10m diameter and a 10m length, built by St. Jashka & Sohn from Vienna, produced steam with a pressure of 7 atmospheres.Pressurised water was distributed along the port main axis through a 6.8 km long system of cast-iron pipes, installed in underground passages that could be inspected.The hydrodynamic plant - a rare example of machines that worked for more than a century - is located in a Rundbogenstil building, an architectural style that was a German version of Romanesque, very popular at the time.The architectural features of these monumental buildings lie in the vertical and horizontal lines along the facades, in the geometric definition of the basements, the doors, the windows and all the elements of the architectonic language of this complex.Each building is an example of the technical architecture at the end of the 19th century, a period of transition for the construction principles and configuration of maritime structures, which were adjusting to a defensive function and to the new trend of equipment mechanisation.Because of the length of the building the design included two main stairs leading to the higher floors, seven elevators, eight lifts and two internal hatchways connected with the cellar.