Below is just a rough sketch of what I would do to start. The blue lines are where I would put portals. The orange where I would add structural/world brushwork to close it up. Make the structural/world brushwork go from floor to ceiling of the sky box and the outdoor portals do the same.

Also, "grid" portals do nothing. It is a waste of time. You must base them off of soundly laid out world brushwork. You may need to alter the map to better accomodate portals and improve your framrates. Remember that your TRI counts should stay below 60,000 as much as possible.

I understand that but when I try to portal like in the above sketch I get the error "overlapping portals"

How do your portal walls intersect with each other?

ps I seen all the tutorials and did forum searches

The BLUE portal face should never intersect with another. They can touch, but should never cross over. If you do full portal walls outdoors, from sky box floor to top, and then have the portal touching a world brush on each end, you should be fine. If you also try to portal a house INSIDE the larger outdoor portal, you may get problems as well. Best to not portal the house as it is one small area inside a much larger one.

Sorry to bump an old thread, but I had a question for Slyk regarding the graphic he posted above.

You show portals butting up against the hedges there, but what are they butting up against? I noticed this method in Barbarossa and Townassault, but I can't seem to figure out what texture it is that you're using to butt the portals against. Whatever it is, it is invisible & solid, even in spectate. If it were caulk it would smudge when you move around. What is that?

If you spectate in Barb, you will notice that there are world/structure brush work inside each hedgerow. They are textured with the same sky texture as the rest of the map. That allows all heavy weapon rounds to pass through them, yet they act as portal blocks. You will see the same technique in 'Ponyri' and a few other UO maps.

That helps out quite a bit, thanks!