What is a Ha Ha

A ha-ha (or ha-ha wall) is a recessed landscape design element that creates a vertical barrier while preserving views.

The design includes a turfed incline which slopes downward to a sharply vertical face, typically a masonry retaining wall.

Ha-has are used in landscape design to prevent access to a garden, for example by grazing livestock, without obstructing views.

In security design, the element is used to deter vehicular access to a site while minimizing visual obstruction.

The name "ha-ha" derives from the unexpected (i.e., amusing) moment of discovery when, on approach, the recessed wall suddenly becomes visible.

Read more...https://en.wikipedia.org/wiki/Ha-ha