In 1903 Alcalde del Río had discovered the cave El Castillo, and, as noted, Obermaier carried out excavations between 1910 and 1914. The excavations were continued at various times, intermittently, until our own times, by qualified specialists.[6] Ultimately the investigation was taken up by the archaeologists Rodrigo de Balbín Behrmann and César González Sainz. After the discovery of "La Pasiega" and the first campaigns, the area was little visited — mainly owing to the difficult historical circumstances of Spain in the 1930s.