I'm still thinking about the earthworks of Herbert Bayer, below....
And when outside, a great pile of dirt--an artificial hill, reminiscent of fortifications past, created an elevated viewing space for overlooking the garden and was a logical use for the soil excavated from water features and sunken gardens.
What must have begun as a simple hill gradually took on an elaborate sculpted form, as paths were carved into it for reaching the top, and decorative features were added. Eventually they would be adorned with temples, and even revolving seats for taking the 360 view...an overlook to the garden still, but also a destination in themselves.
(top image, Catshuis Holland, via the amazing bibliodyssey)