The Kalonyktis Koule can be found on Agiasmatsi hill, situated on the outskirts of Kalonyktis village in the Rethymno province. Constructed by the Ottomans after the Great Cretan Revolution of 1866, this large tower was part of an extensive network of towers – known as koules – used to monitor Cretan revolutionaries.

It is likely that the Koules area served as a battleground during the Kalonyktis battle on December 9, 1868. During this time, a group of Cretans led by Petropoulakis were forced to retreat to Roustka by the Turkish forces, resulting in the loss of three fighters. In 1878, the Agiasmatsi battle took place on the same hill, which ended in victory for the Cretan revolutionaries.

Compared to most towers of the same period, the masonry of the Kalonyktis Koule is preserved at a relatively high height.