[XtremeChio]

I have answered this question 3x times today

• Open the MTA and choose MAP EDITOR
• Then go to objects and find Buildings> 'You'll have many types here, just look at each, they have buildings and interiors
• When you're looking at the interior from the outside, it may look as it has no walls. But it has, so select it
• Put it somewhere in the sky or above the sea but somewhere where you will remember it and no one will see.
• Now go IN it by moving the mouse and holding W(lol) and look around. The walls are there, there is no way a player could see he's in the sky
• Now just..start adding objects
• When you're finished, put it in your game mode
• Fly there with a helicopter and somehow get in :P I use Ladmin so I have /move up/down/-x/+x/+y/-y so it's not hard for me
• Do /save 'blabla' and there, you have a file in C:/Rockstar/SanAndreas>'savedpositions.txt' - It's in there

Hope this helps enough, that's it !