Use the Level tool to define a vertical height or story within a building. You create a level for each known story or other needed reference of the building (for example, first floor, top of wall, or bottom of foundation). To add levels, you must be in a 3D view. When you add levels, an associated plan view is created.
Levels are finite horizontal planes that act as a reference for level-hosted elements, such as mass floors. You can resize their extents so that they do not display in certain views. For more information, see Datum Extents and Visibility.
You can hide level annotations after you add them. For more information, see Hiding Elements in a View. To learn more about levels, see 3D Levels.