Stone stairs.
Effects Allows you to go up a level.
Type Building object

Stairs can be made from Carpentry or Masonry, and allow you to go up one level. They can be destroyed in one hit.

See Holes.

You are allowed to use stairs to climb walls, yet, if you use stairs to pass over water you are bug abusing, as you can't climb water.  If you try to climb water, you will land in the water.