“Invisible Woods” is an interdisciplinary project involving ecologists, archaeologists, art historians, engineers, and architects. The challenge is to engage these different mindsets and converging that knowledge to the dendrochronological process and use it for study and examination of timbers preserved in historic buildings and archaeological sites, including rescue operations. I would like to introduce our project and selected case studies we’re working on, from the archaeological interventions on the riverfront of Lisbon to national monuments such as the Convent of Christ (Tomar) or Monastery of Santa Cruz (Coimbra). Examination of timbers will help us to identify wood species used in the past, their provenance, precise dating, and to understand construction techniques with possible structural changes, which will confirm (or not) archaeological and archival information. This will be a starting point for organization and development of tree-ring archive for Portugal with the intention of using it, among others to trace old trade and commercial routes in the Age of Discovery or to follow change of climatic and ecological conditions in our part of the Atlantic Iberia.