The Byzantine style monastery Nea Moni (new monastery) is dated from the 11th century. Nea Moni is the result of a fulfilment of a promise from Byzantine emperor Monomahos. When Monomahos lived in exile on the island of Lesbos. He promised to the holy icon of Theotokos, he would build a monastery on the place the icon was found when he would become emperor. Two years after his promise he indeed became the Byzantine emperor and ordered his best architects and artists to build Nea Moni. The construction had taken 12 years. However Monomakhos died before it was completed and didn't be able to see its full glory.
The construction is similar to monuments that can be found in Constantinople, and its typical octagonal style can only be found on Chios and Cyprus.
The entrances were made of marble, inside the ceilings were covered in gold mosaic. The mosaic themes amongst others are the Pantocrator, moments in the life of Christ, the archangels Michael and Gabriel.
Unfortunately a lot of Nea Moni's glory has been destroyed by the Turks in 1822 and by the earthquake of 1881. The monastery is now under restoration.