Camelot Unchained is not something that can be done in just one sitting, so Mark Jacobs broke it into two. In the first update, Jacobs described the building blocks, mining, and the cooperative nature of construction. The conclusion of this two-part series focused on explaining blueprints and how RvR is intertwined in the world-building system.
Blueprints, which can be traded, are a way to speed up the building process -- or rebuilding, if enemies have destroyed your structure in RvR. Players with the appropriate skills can create blueprints of an already finished structure or through the architect's interface as a plan for a future structure. Through RvR, players can claim buildings built by others, either by deconstructing the entire thing or just capturing it; those structures can then be repaired or rebuilt by the new owners.
Want even more information on building a fortress in Camelot Unchained? Then check out Massively's interview with Mark Jacobs.