Above the village of Sangri, you can make out the ruins of Kastro Apilarou, which is the castle the Italian conquerer, Marco Sanudo, who conquered Naxos after the 4th crusade. The castle was the defensive stronghold for the region but locals today still say its a bit of a mystery about who the Apilaros family really was before Sanudo came and took over. If you do make the tough climb up to view it up close, you'll be greeted with fantastic view of the Naxian plains.
On Mt. Profitis Ilias, Sangri, Naxos, 84300, Greece