These are usually set up near the building in order to attract the lightning strike and then neutralize it before it travels back into the ground. By having it travel into the ground, essentially it will dissipate and not be of any danger to the building or surrounding trees at all.
You can get an older style lightning rod put in place, or something that is a bit more modern instead.
The more modern models are basically made up of a series of small copper and aluminum spikes which are now called air terminals.
These air terminals are mounted on the highest points of a house or a business building, usually, at the top of the roof, a chimney if it exists, and other high points on dormers. One building can have as many as ten or more, depending on its size and shape. Not to mention, if there are many high points, you can fit many on the roof.