Simple 3D Art
With the tagging schema "Simple 3D buildings" you may describe complex buildings for rendering in 3D. At certain places this is used extremely, not only to shape small details of buildings but to show artful objects. The building:part=* is used like in MineCraft or as Lego blocks. The roof:shape=* is used to structure sides.
A slippy map user will never see them. This page shows some remarkable examples of them. Because it's hard to decide what is the more beautiful object, they are ordered by complexity / the number of tagged "building:part"s.