Well, like you said, getting out of the atmosphere gives you the option of using a rail-gun (electronic catapult), but you could launch satellites from the roof

Well, like you said, getting out of the atmosphere gives you the option of using a rail-gun (electronic catapult), but you could launch satellites from the roof a tall building, the same way. A 100-mile wide, 100-mile tall cylindrical building could have a circular track on top, or spiraling up to the top, that could perhaps be long enough to accelerate objects to orbital velocity.