One of the most valuable secrets and curiosities of Vigo are the old underground tunnels under the Castro fortress.

The mayor of Vigo, Abel Caballero, has commented that he would like to open them to the public when they are enabled and prepared for it from the point of view of safety and the continuity of the tunnel, which seems to be blocked at many points.

It is believed that these tunnels were built at the end of the 17th century in order to hide there from the continuous invasions that the city suffered. In addition to being able to store there the belongings, treasures or valuable products at each stage in which they were used.

It is thought that the underground passageway goes from the Castillo del Castro to the Castillo de San Sebastian, where the Plaza do Rei and the Concello are currently located. Formerly there was a military base there in what was once the Campo de Granada.