No one can give ideas in a vacuum. How the garden relates to the house, what climate you are in, and what you use the garden for are some things needed to start. Pictures also help.

I envision a container garden in an office building.

pavers, various container plants depending on the location/season.

a bench, small table, waterfall. Lattice for privacy.

Do you want to sit in it or just look at it? With that small a space you will have to pick a priority.