Building a basement
On a new lot, put down staircases to lower the terrain and go to the bottom of the first one. Miss out one tile and put down another staircase, then repeat this once more and you should have three staircases. Delete the staircases and use the "Level Terrain" tool to level the terrain from the lowest tile. Set it as large or small as desired. Using the "Straight Line Wall" tool, build walls around this hole so that there are walls pressed up against hills. Build the room above so that it covers the entire basement. Cover around the house with the "Foundation" tool; all the slopes should be covered up. Place one tile in the top floor then create a staircase leading down to the basement. Make two or more foundation blocks at the front of the house, and place a staircase leading up them.