Berlin's pink pipes: What are they?
Anyone visiting Berlin is likely to notice the giant pink pipes that snake through the city for miles on end.
The brightly coloured tubes form elaborate shapes as they make their way through the German capital, many of them above head height.
But what are they and why are they there?
Our correspondent Stephen Evans followed one of the pipes to its source to find out.
The Close-up series focuses on aspects of life in countries and cities around the world. What may seem ordinary and familiar to the people who live there can be surprising to those who do not.
Video journalist: Suraj Patel