Because if the axis wasn't tilted the sun wouldn't shine on the top of the earth.
A wall stands using gravity. It is constantly being pulled down. Many also place them in ways that they dig into the ground, and almost make a socket just for the wall to be placed, using the land that is there. More and more walls are placed and eventually, they make flooring and a roof.
Hope that helped!
C the shape of rock deforms :))
China for Southwestern Pacific, but US, Brazil, and the EU are top producers
