The castle of Myrina or castle city is placed in an exceptional position at the west side of Myrina and is one of the most well preserved castles all over the Aegean Sea. Myrina was first inhabited in Neolithic era. 

On the rock there are remnants of the first houses and a part of the Cyclopes walls.   The building material of walls was used afterwards by Franks and Turks in the manufacture of other buildings.

The Byzantines built in 1186 a small but powerful castle by which however are saved a few parts. The period of Frank occupation repairs were made by Filocalo Paolo Navigaioso, Big Admiral of Romania, in 1207-1214. For this phase of repairs informs us a marble plate with the lion of Venice

          

The castle is built in rocky and steep peninsula and communicates with the land only from Eastern. By the two sides of narrow isthmus that connect the peninsula with the land is shaped harbor. The northern side borders on the Greek district Romeikos Gialos and the southerner on Turkish (Tourkikos Gialos).

The main gate of the castle leads to the south part of it. A second gate leads to the north part while a third gate, smaller in size, is placed western. The surrounding wall has 14 towers. Most of them are round or petaloid. There are also some rectangular towers also.

The walls of the castle are build with volcanic stones, main characteristic of the island. The appearance that the castle has today is a result of  many structural stages.