Forgotten Functions: Grid Systems

https://helpcenter.graphisoft.com/user-guide/135248/One of those great forgotten functions in ARCHICAD like automatic dimensions.

Grid System (Design > Grid Systems)

https://helpcenter.graphisoft.com/user-guide/135653/

This is a great way to place your grid and also have it place the columns, beams and grid dimensions.

Place a Grid System.

https://helpcenter.graphisoft.com/user-guide/135248/