security4

Hey guys I need some help at my work we have 7 buildings all connected via long hall ways, I have several cameras already in place that need to be hooked up.. Each building has a Electrical room that I want to run the wires to, so what I'm asking is how can I get the signal from each camera in the Electrical room to our main building/ my office with out running cables all over the place? I was looking to into wireless but because the building are so spread out the signal would never make it.