To rotate the column during placement
You can add columns in plan views and 3D views. The height of the column is defined by the Base Level and Top Level properties, as well as offsets.
Structural Column. Where is it?
Structure panel
Column
Build panel
Column drop-down
Structural Column Columns snap to existing geometry. When you place columns at grid intersections, both sets of grid lines are highlighted.

While placing columns, use the Spacebar to change the column orientation. Each time you press the Spacebar, the column rotates to align with the intersecting grids at the selected location. In the absence of any grids, press the Spacebar to rotate the column 90 degrees.