Augmented reality is allowing visitors to the Berlin Wall to see it as it was before it came down in 1989.
The free MauAr app (a play on the German word for wall: die Mauer) shows how the Wall changed and grew over the years, from a relatively low structure to the towering concrete barrier that divided east and west, and what life was like beside it.
Holding your phone or tablet up towards where the Wall was, anywhere in Berlin, makes it appear, overlaying images on the real world. App creator Peter Kolski explains: "You get to understand the history. And what I think is fascinating is that when you put the smartphone away, then you still have the impression that the objects are still there. And then you have a contact to the real world."
Kolski himself grew up in what was West Berlin and remembers the Wall as ever present. "Of course I didn't really understand what the wall was. It was the end of the world I though. You could look left and right but you couldn't see anything ahead and it was without an end in both directions."
Berlin is the third most popular tourist destination in Europe after London and Paris. According to Visit Berlin, 34 per cent of tourists visit the city to learn about its history, and 58 per cent to see sights, including the remnants of the Berlin Wall.
Hannah Berger, spokesperson for the Berlin Wall memorial, says it is important to maintain the memory of what it is like to live in a dictatorship.
"With the remnants of the wall and the original wall pieces we can explain how the border regime of the East German state worked. And then you understand what it was like to live in a dictatorship and also then in turn what it is like not to live in a dictatorship, and how valuable freedom, democracy and human rights are."