Gabion walls don't need any kind of drains because they are porous throughout. Gabions can be customized to make them more useful in public spaces. Gabions can be filled with any heavy material--diverse stones, metal artifacts, obtanium, etc.
SECRET GARDEN In Arlington, Virginia, architecture firm Höweler + Yoon contends with spatial and budgetary constraints to carve a microcourtyard, complete with Japanese maples and a cascading concrete fountain, in just 200 square feet.
Fountain by Isamu Noguchi for the 1970 Osaka World Expo. This was one of nine fountains he designed for the Expo. “One day…I had a vision: I saw the Earth as sculpture.” Noguchi often said that the space around a thing is as important as the thing itself.