Side Trip from Lisbon: Grutas de Mira de Aire

In 1947, locals in the town of Mira de Aire discovered the caves which were found to be over 11 kilometers (almost 7 miles). When news of the newly discovered caves reached Lisbon, speleologists (scientists who study caves), descended on the town and began their research of the natural formation. At first, they would go down into the caves by lowering themselves with ropes. Stairs, first built out of wood, and later, out of brass, were used to access the caverns. Public interest in the caves was intense, so more stairs, platforms, and safety measures were put in place. The caves opened to the public in 1974. <a href="https://destinationeatdrink.medium.com/side-trip-from-lisbon-grutas-de-mira-de-aire-9f7a447209bf">Website</a>