Chania was fortified with walls and a moat (which was never filled with water) by the Venetians in the 16th century to protect the town because of the spread of the Ottoman Empire in Eastern Mediterranean.
The walls were built to the designs of the Veronese, Michele Sanmichielli. They were square in shape and each of the four corners were amplified with heart-shaped bastions.
They had three gates, one in the east known as the Sand Gate (Porta Sabbioanara) in Koum Kapi, a small one in San Salvatore bastion, and the main one, Porta Retimiota, in the south part of the walls.
In the early 20th century, parts of the walls were demolished in order to expand the town.