Commercial tower sites have the Single Point Ground right where the coax/Heliax enters the building.
A very good place to put your lightning arrestors AND coax switches. (I use both, I.C.E. (Industrial Communications Engineers) And Polyphaser arrestors and the coax switches that put unused antennas to ground all mounted on the same copper sheet. (I use the switches for antennas I plan to never operate during a storm, Or if I do plan to operate a particular antenna from a switch during a storm, That antenna line will also go through an arrestor)
(I use mostly Alpha-Delta coax switches, But do not trust the "Arc-Plug" in them for real protection.
I run the lines of any antennas I plan to operate during a storm through either the Polyphaser or an I.C.E.)
(I live on a hilltop with tall towers, And DO take direct lightning strikes most every large storm. Never had any damage to equipment with this system.)
I make up the Single Point Ground panel by getting a sheet of flat copper material (.026" thick) from a local heating/sheet metal shop. The last one I made up was almost 3 feet by 3 feet square. Plenty of room to install lots of arrestors and coax switches. (The copper sheet is screwed to a piece of 3/4" thick plywood to provide material to screw the switches and arrestors to)
That large copper sheet is attached to a 6 inch wide copper strap that runs directly outdoors to the ground system. The ground system consists of a number of ground rods (Normal spacing is about twice the distance apart as the depth. (8 foot deep rods should be spaced about 16 or so feet apart in normal soil)
That 3 foot by 3 foot sheet I have provides space for LOTS of runs of coax, And leaves LOTS of space for future antennas! A typical ham station could get by with a much smaller sheet. Even just running a one foot or so piece of the 6 inch wide strap on the wall would be large enough for several switches and arrestors.
For some good info: http://members.cox.net/pc-usa/station/ground0.htm