A barracks in the free game C-evo is a building available as soon as you research Warrior Code (which you need before designing any new ground units). Troops built in a city with a barracks start life hardened. Troops stationed there double their health each turn until reaching 100%, which is a distinct improvement on the 20 percentage points increase that applies to a unit with over 20% but under 80% health in a city with no barracks. (The matching facilities for air units and naval units are Airport and Dockyard.) Unlike the counterparts in Civ1 and Civ2, barracks never become obsolete.