The concentration camp of Cardeña Historical milestone · Castrillo del Val, Burgos (Alfoz), Burgos Image of Castrillo del Val, not of the place itself. During the Civil War the monastery was turned into a concentration camp through which more than four thousand Republican prisoners and international brigade members passed. The Trappists did not occupy it again until 1942. 1938 Photo: Maintenance script (CC BY-SA 3.0) What to see and do in Castrillo del Val