The works of restoring the wall started in 2017, implementing the studies approved by ESMA and KAS the year before and concentrated on the areas B17 and B12-B13 of the Acropolis wall.
The first intervention area is the area Β17 (27,500 – 35,000) of the north wall, in the position of the NW building. A large part of the Themistoclean wall is delimited in the east by an Ottoman buttress and in the west by the part restored in the 18th century. The ancient wall in this area was constructed by carved blocks of Piraeus limestone (Actites) erected in an isodomic way. In this area the wall has retained a height of 10 layers in its interior, while only 6 layers remain in its exterior, since the highest part has been restored with the use of ancient blocks taken from another place. In the middle of the height of the exterior sidewall, the construction is totally damaged and some blocks from the 7th and 8th row have fallen off.
Restoration works, following the approved study of K. Mamalougas and D. Michalopoulou, include fillings with new stone that adhere to the ancient structure. It has been suggested that on the west section of the area to be restored, where a late Ottoman restoration is found, the existing mortars should be replaced and the block joins be grouted with the appropriate and compatible materials chosen after a relevant investigation.
Works should also be carried out in the areas Β12 (34,000 – 42,000) and Β13 (0,000-4,000), in the north of the Erechtheion and above the row of uncarved drums of the Pre-Parthenon which were incorporated during the construction of the Themistoclean fortification wall. This particular area has retained its full height of 15 rows and was restored and filled during the Balanos restorations, when cement mortars and iron elements, by now oxidised, were used. The wall in this area presents problems of corrosion, broadening of the horizontal block joints and fractures
The restoration study, conducted by A, Hadjipappa and D. Michalopoulou, aims to structurally restore this part of the wall and to reassure its static adequacy and aesthetic enhancement by removing the most recent fillings and also the oxidised iron elements and cement mortars. In particular, it is expected to structurally restore the ancient limestone blocks and systematically conserve their surface, to fill 6 ancient limestone blocks with new stone and add new blocks, replacing as such the ones used unsuccessfully in the Balanos intervention.
The choice, design and implementation of the intervention materials for the walls and specifically the mortars, which were firstly used in the completed project on the south wall in 2015, depended on a thorough study and analyses of historic mortars of the region. Stones from Pitsa Korinthias were used for the fillings. A further research of the materials was conducted in collaboration with the National Technical University of Athens and the Centre for Stone of the Directorate for the Restoration of Ancient Monuments (DAAM).