The impressive medieval stronghold of Koules still remains at the base of the western breakwater of Heraklion’s modern port. Originally named Rocca al Mare by its Venetian founders, Koules, also known as the Great Koules, was not the only ruler of the port. A smaller fort, the Small Koules, once stood opposite it on today’s marina pier until it was demolished in the early 20th century to make way for the pier. Furthermore, Koules was constructed on the site of a previous round tower with battlements.

Observing the fort’s evolution as both a structure and a historical determinant is fascinating. During the Minoan Era, Crete faced no external threats, so there was no need to fortify the coastlines. This situation persisted through the Roman and First Byzantine periods. However, the emergence of pirates in the Mediterranean Sea led to the necessity of fortifying cities and ports. The Byzantines were the first to fortify several locations in Crete, but not to the extent required, as they were preoccupied with internal issues. As a result, Crete was easily conquered by the Arabs in 824 AD, who looted and destroyed the forts.

The Arabs fortified Heraklion, renamed it Kandax, and used it as a base for their pirate raids. After several unsuccessful attempts, the Byzantines recaptured Crete under the leadership of Nicephorus Phocas in 961. However, 250 years later, Heraklion was first conquered by the Genoese and then by the Venetians after a few years. The new rulers constructed impressive new walls and named the city Candia or Grand Castle. To enhance the harbor’s security, they built the renowned fortress of Rocca al Mare, meaning the Fort of the Sea, which was initially a small tower, as mentioned earlier.