The HDA expects 3 INPUTS:

• 1st INPUT expects a TERRAIN
  tip: generate terrain by inputting a grid (increase division for more detail).
  give the terrain a mountaineous look by deforming it with an AttributeNoise)
  
  
• 2nd INPUT expects a CURVE
  This curve will decide where the wall will be build onto the terrain
  
  
• 3rd INPUT expects a BOX
  Whereever a box intersects with the curve a watchtower will be generated.
  In the viewport place your box(es) by use of moving the gizmo in the XZ plane, so that it intersects with the curve you created.(Insert multiple boxes by merging them in a merge node and connecting it to the third input).

THE HDA OUTPUTS:

• DENSITY MAPS of the wall, placers and terrain.
  
  
• GEOMETRY GROUPS of all the assets and its details are provided, which
  can be used to texture the asset.
  
  

Software used:

• SideFX Houdini
• Autodesk Maya