When Greece gained its independence in 1832, its borders crossed the Ambracian gulf; the south shore belonged to Greece, while the north shore remained under Ottoman rule. Koronisia was an island at the time and the Ottomans erected a gun fort to control their side of the gulf. The fort was built in 1860 (as noted in the inset plaque above the arch of the doorway) and consists of a two-storey circular tower with two semicircular extensions to the east and west. The entrance is reached by a stone ramp and wooden bridge. The powder magazine was at the center of the ground floor while rifle slits and three large gunports allowed the defenders to fire at any approaching enemies.