There are a total of 14 cult properties (Silos) in Holland Valley, 16 cult properties (Shrines) in Henbane River and 10 cult properties (Wolf Beacons) in Whitetail Mountains.
BUG ALERT: If you die whilst destroying a cult property, the property will get destroyed but the game won’t count that property as destroyed. Thus, your side mission will remain unfinished. Far Cry 5’s Patch 1.06 released by Ubisoft is supposed to fix this problem.