50 years ago, Máximo Alonso was ploughing a field when the ground suddenly gave way. This was the lucky chance that brought the Castañar de Ibor cave to light, and to the attention of the worldwide scientific community, in 1967. Today, Mr. Alonso's children received a plaque on his behalf, in tribute to his efforts to draw the attention of local officials to his find.
The cave is one of the few natural heritage sites in the region, receiving 10,000 visitors in 2003 - 2008, but visits then had to be restricted to scientists and academics due to its fragile natural balance. In 2014 it was opened to the public once again, and guided tours are now available for small groups, from May to September.