During fifteen days of June 2015, the team of l’Esquerda worked in a research project to build a Carolingian wooden watchtower on the River Ter, in Roda de Ter, Catalonia, Spain (This Research Project was approved and granted by the Spanish Ministry of Culture (DGICYT, HAR2012-36497) for three years 2013-2015.). The idea was to test our hypotheses experimentally, (a) if the wooden watchtower could be built without any metal nail, (b) how it worked, and (c) its resilience.