I was years ago involved in helping to evict some ghosts from a hotel. Basically it's the same process as evicting negative entities from your own person (see my thread answer
here).
An environment holds the energy of the stronger forces. Whatever energy is put into it and continues to be reinforced there, becomes the dominant force field. What we do alone when we do it together becomes so much more powerful.
When I think "pagan" I think of indigenous really, as it goes back to the dawn of humanity. People have come up with all kinds of rituals but the power is in each one of us and we are all connected.