Often a Renaissance palace had deer or other picturesque
animals in front of the palace. But a problem arises: how
to keep these picturesque animals in front of the palace,
and how to keep peasant cows and pigs, etc. from wandering
to the front of the palace. A simple solution to this problem
is to use a fence. However, fences are themselves not that
beautiful. Instead, a "ha-ha" may be used. A "ha-ha" may be
thought of as an inverted fence: instead of projecting above
the ground, the "ha-ha" projects below the ground (and out of
sight).