A conscription center (abbreviated CC and also called "barracks") is a city upgrade which raises manpower and doubles the recruitment capacity in its city. Conscription centers are shown on the main map by a large gray tent, and shown on the city screen as a larger, spikier version of the normal recruiting tent.
To build a new concription center, go to the recruitment screen and select the same-named button. Conscription centers cost a variable amount depending on how many CCs are already built and/or being built. The base cost is 1000 ducats, plus 250d per already existing CC or CC project. 24 months are required to complete the project. If the city is captured while building, the project fails and the money is lost.
Two countries, the Ottoman Empire and Sweden, typically gain a conscription center by scripted event long before they have the tech to build them. Several other countries may gain a CC by scripted event, although the choice is not a likely one for the AI. There are no random events which give conscription centers.