The volume includes a selection of the the lectures of the 15^th edition of the Conference Series on Theoretical and Practical Issues on Built Heritage Conservation – TUSNAD 2011, which was held in Alba Iulia and Şimleu Silvaniei, on the topic Fortresses once again in use. The lectures and the discussions were centred around the complex problem of the protection of fortresses, being presented questions and solutions connected to their inventorying, research, conservations works and rehabilitation programmes.