During the Genoese domination, at the period from 1346 until 1566, and while the pirate raids was continuously increased, the Genoese, in particular the “Maona” who had obtained dominant rights over the lands and in order to preserve the agricultural production of the mastic and its trade, was forced to reorganize  the fortification of the village. Initially they built the external walls around the village with crenellations and small towers at the corners leaving only one central entrance gate, while at the centre of the village was constructed a huge square tower. Then they manned the fortifications with military garrison so to guard the village twenty-four hours protecting it from each external danger. By the end of 14th century and the beginning of 15th century Mesta has been transformed to an actual castle so to protect effectively the village cultivators from the pirate raids. Such a castle form acquired and the nearby Mastic villages like Olympoi. During the Genoese domination Mesta had a lead role as the nature gifted it with the benefit of a natural seaport and the Genoese utilized it for trade and military purposes many times. There are sources that make reference of military operations that commenced from Mesta. In 1432 Tomaso Giustiniani from Genoa landed an army at Mesta seaport when the Venetians who was in competition with the Genoese had laid siege at the city of Chios. According to the sources during the Genoese occupation the seaport was named “Porto di S. Anastasio” (port of the Saint Anastasios) dedicated in his memory.