The Colosseum

Apparently, over 5000 different types of exotic animals were killed in sport here during its heyday. A movable wooden floor covered in sand to soak up the blood concealed the animal cages and sophisticated technical apparatus, from winches and mechanical lifts to ramps and trapdoors.  These contests were also used to eliminate slaves and proscribed sects, Christians and criminals, political agitators and prisoners of war. 

With the fall of the Roman Empire, the Coliseum fell into disuse.  The ruins were plundered to create churches and palaces.  Apparently, this was an early sustainability practice!  HA!