They're a regular roadside sight in Spain. Huge black bulls dominating the skyline. But why are they there, and who put them up in the first place?

Blogs from my balcony! Eating and drinking in Spain, great places to see, plenty of history and cool facts. All from the nicest town on the Costa Blanca!
They're a regular roadside sight in Spain. Huge black bulls dominating the skyline. But why are they there, and who put them up in the first place?