Building on a hilly terrain

I am trying to develop building on a contoured do I use spline to make contours.
Please share your observations.

You may find this useful:

Remember Lofting requires every shape to be a Closed Shape

Sketch the Contours on the X-Y Plane

Select all but the Largest Contour and use Transform > Move/Rotate to elevate them along the Z Axis

Deselect the Larger of these Contours and repeat as required.

Remember Multiple ‘Peaks’ cannot be Lofted at the same time.