Friedensreich Hundertwasser is an Austrian artist and architect who has gained world wide renown. Some of his more profound ideas include:

Covering the roof of any building he constructs with grass, meadow, or even trees, so that when the building is complete there is a zero sum loss of natural space

A brilliant composting "humus toilet", easy to install and operate that turns human waste into fertile soil over a period of time. The system is odorless and can be used in both rural and urban settings.

Allow for "tree tenants" in large apartment complexes. Basically the idea that a room be ceded to a tree, which is grown sticking out of the window. The tree pays its rent by purifying the air and water.

A renter's right to decorate the outside of their apartment as far as their arms can extend out the window. This has resulted in some very lively and colorful facades on his buildings.

His projects have included:

A church.

A health spa.

Roadside gas station/truck stop tourist center.

Stamps.

New (un-adopted) flags for Austria and New Zealand.