Squatting (living in unused buildings without owning or renting them), is legal in Holland for houses which remain empty for longer than one year probably because it helps temporarily shortening the long housing waiting-lists.
Squatting has also a political background since it is also seen as tool to protest against the outcomes of capitalism.
Those photos are taken during a demonstration by a group of squatters in the Dutch city of Utrecht against a proposal from the Dutch Christina Democrats Party to forbid squatting.