If you're talking about the Embedded Tower (which is where you get Kyogre (HG), Groudon (SS), and Rayquaza (if you have both Kyogre and Groudon from HGSS)) then it is located on the route that takes you to the Safari Zone. Go down the ladder and go out. Go left and go through the passage way in the rocks. Use rock Climb to get up and go in the cave or go left and rock climb for an Item ball.
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The Red Orb summons groudon to the Embedded or Hidden Tower off of Route 47.
The Bell Tower is in Ecrutek City (where you get Ho-oh)
Magmar have it. They can be found in burned tower.
So simple
In the upper left corner of Ecruteak city.