Marco Sanudo of Naxos: Marco Sanudo was a nephew of Venetian Doge Enrico Dandolo and a participant in the Fourth Crusade. With his keen interest on the island of Naxos, he arrived at the harbor of Potamidides to the southwest of Naxos in 1207 along with eight galleys loaned to him by the Venetian arsenal. The locals put up a good fight but Marco Sanudo successfully captured the Greek fortress of Apalire after a five-week siege. Slowly moving forward he eventually managed to capture the entire island of Naxos as well as other Cycladic islands by 1209 and pronounced himself as the Duke of the Duchy of Archipelago in 1210 with Naxos as its capital.
Marco Sanudo fortified Naxos and divided it into 56 provinces. He introduced a feudal system whereby each of the provinces was distributed and assigned to those who had helped him in his crusade as well as those who came in from Venice to fulfill administrative duties. This system was quite easy to introduce as the local Greeks were already used to the Byzantine pronoia.
Marco Sanudo gave away most of his captured islands to those who had assisted him in his endeavor as fiefs. His cousin Marino Dandolo received Andros, Andrew and Jeremiah Ghisi received Tinos, Mykonos and the Sporades, John Querini acquired Astympalaea, Jacob Bertozzi received Thera and Leonardo Foscolo received Anaphi. Other islands, including Naxos, Paros, Milos, Sifnos, Kythnos, and Syros, remained under Marco's power. Marco Sanudo died in 1227 and his reign was followed by that of twenty-one dukes from the Sanudo and Crispo dynasties.
Naxos was one of Marco Sanudo's favorite islands and he played a pivotal role in its subsequent history and culture. He made Naxos the administrative center of his duchy and it continued to be the state's nerve center until it fell under the Ottoman rule in 1566 A.D. Sanudo, with the help of a group of trained engineers built a wonderful specimen of medieval architecture, the Kastro.
The Kastro was essentially a walled city within a pentagon-shaped defensive wall. Marco chose the highest point above sea level, a site of an ancient citadel to build the Kastro. At the center was located the Catholic cathedral and the Cagellaria or administrative tower. The nobles usually built their houses here. Originally there were five lookout towers of which only one remains today. The Kastro had three entrances, one to the north, one to the south and a third to the east of the Kastro.
After his death, his descendants invited locals to come and build houses near the Kastro establishing a new neighborhood that was called the Bourgos. As the Duchy expanded and the need for space grew, more and more houses were built with the Kastro as the center of this urban development. Marco Sanudo was a wise ruler and truly cared about the well being of his subjects even though he was from a foreign land. He had thus rightfully earned love and respect from both his Venetian and Greek subjects.