One of my current favourite things in the landscape are Gabion retaining walls. Mainly used in civil design (side of highways), these are heavy wire cages usually filled with rocks to form a strong retaining wall that allows stormwater the freedom to move through safely without erosion.
There is a freedom in this landscape element, with the flexibility to use any appropriate material to fill the cages to suit and enhance any design. Gabions can be used as free standing elements, not just for retaining walls and bank stabilization. Organic shapes can also be achieved within the formation of the gabions. These modifications create a very versatile landscape element that is unique and exciting.