In 1914, malaria was a serious public health threat to the people of San Antonio, Texas. Dr. Charles Campbell figured that the best way to reduce the mosquito population was with bats. So he built this giant roost for bats to live in.

But what do you do if you've got too many bats? Then you need to attract eagles with knives -- as many as possible -- in order to kill off the bats.

Link -via Offbeat Home | Photo: George Grantham Bain Collection