The impact of the sea-corrosion on the monument and on the materials of the restoration of the ‘70ies was already obvious by the beginning of the second millennium. From 2003 onwards the 13^th Ephorate of Byzantine Antiquities prepared a restoration project to deal with corruption of the battlements, deterioration of the stone surface and mortar fillings, cracks, insoluble salt crusts, corrosion of the iron parts, (i.e. the reinforcement of the concrete roofing of the terrace buildings, the clamps holding together the decorative elements, such as the marble emblems of Venice on the facades, and the iron parts of doors and grids of the canon-openings), the penetration of rain and sea water through the skylight windows and the sea humidity, the corrosion and destruction of the electricity and water installations and the absence of adequate visitor facilities. In 2010 two separate plans of the Ephorate, for the restoration of the building and the conservation of the stone surfaces respectively, were approved by the Ministry of Culture.

The project for the “Restoration and Conservation of the Venetian Fortress (Kules) of Heraklion”, which lasted from 2011 to 2016 was financed by the NSRF with 2.050.000€ and by the State Fund with 120.000€. The campaign was initially conducted by the Fund for the Management of Credits for Archaeological Works, and from June 2013 by a Scientific Commission subjected to the 13^th Ephorate of Byzantine Antiquities (actually Ephorate of Antiquities of Heraklion). The project included three categories of interventions; a. restoration of the building, b. conservation of the stone surfaces, c. visitor facilities. More specifically, during the restoration campaign the walls of the building were reinforced (new mortar fillings, stabilization of structure through injections, masonry fillings), the roofs of the terrace buildings, the battlements constructed in the ‘70s and part of the parapet were demolished and reconstructed, the battlements’ corridor was restored, the skylight windows were replaced, the iron parts and clamps of the doors were replaced with stainless steel and the wooden parts were conserved, the shutters of the cannon-openings were replaced with windows and their iron grids were replaced with stainless steel. The surface conservation works included chemical and mechanical cleaning for the removal of the soluble and insoluble salts (black crusts) and stains of bio-deterioration, stabilization of structure, filling of cracks, adhering and joining of broken parts with titanium bars.

To improve visitor facilities the hygiene facilities at both ground level and terrace were fully reconstructed, equipment for a refreshment point and a small open-air theater on the terrace was provided, new electricity, water, drainage and internet infrastructures were installed, a full access to both levels of the fortress for people with disabilities was granted, a small congress and projection room was created at the ground level, info points and information panels were placed, a web-site applicable in mobile devices was designed and finally, two study rooms for scholars of sculpture and pottery of the Venetian era as well as an exhibition dedicated to sub-water archaeological research in the gulf of Heraklion were created.