Terrain Wall around large raised planting box connected to brick building

[GardenerInNYC]

I am a new user trying to show a large 6'x 24' planter box with 12" thick walls attached to the corner of our NYC building.  I used the Terrain>Garden Bed feature to raise the terrain elevation inside the box to 26" above the sidewalk and have been able to place plants as I wanted.  I created a 28" high Terrain Wall around this and surfaced it with sandstone using Terrain path.  My problem is the 3D view shows the walls (which are a horizontal 28" on both sides) angling down at each end to almost ground level.  At the corner where the two walls meet they also form an angle rather than a vertical face.  

 

Perhaps Terrain Wall is not the right way to do this?  Any help would be appreciated.  I am using HD Suite for this so I can show building management the look of this bed in front of the windows and brick and sandstone walls, and to also show the residents in the ground floor apartment the view of the garden bed out of their window.  I have two more larger raised beds to design that can be viewed from lobby picture windows so it would be great to be able to work this out.     

[GardenerInNYC]

Thank you for the guidance Eric.  Hoping that below are the screen shots and the signature showing that I have Home Designer Suite 2020.  I am new to the program and have spent quite a few hours over several days with the various resources trying to get the hang of it.  Obviously terrain in an issue I am trying to get my hands around.  Dan 

 

[solver]

I would use Soffits instead of a terrain object. 

[GardenerInNYC]

Wow.  I was stuck on external tools and would never have thought of that.  5 minutes and I have my image.  Now I can refine that and move on to the harder beds off the lobby.   Thank you.   

[MasterFR]

I would recommend using a slab. It can be shaped and height set just like a wall, and has terrain related settings (e.g. bottom is 12" below terrain). It can also be shaped to create straight/angled/curved walls as needed. Then choose a material (i.e. make it look like retaining blocks, bricks, rocks, wood, etc). That is how I do it, works great, especially if terrain is still being adjusted/changed, though you also have the option to lock the height/position in relation to the building (ignoring the terrain) too. That way it works for both raised beds connected to the building, and raised beds that are independent and away from the building.