The volumes n. 13, 14, and 15 of Defensive Architecture of the Mediterranean Book Series (edited by M. G. Bevilacqua and D. Ulivieri) collect the proceedings of the sixth edition of the International Conference FORTMED 2023 Fortifications of the Mediterranean Coast, hosted by the University of Pisa, 23-24-25 march 2023.<br />The conference aimed to share interdisciplinary research and works on the knowledge, conservation, restoration, and enhancement of the historical military architecture heritage.