Hidden in the foliage of the wooded areas of Norra Djurgården, a string of 48 massive cement blocks stand sentinel between two bays. Called “concrete pianos” for their shape and form, these 17-ton blocks were placed in the suspected path where Russian tanks were likely to invade during WWII. Björn Larsson followed the three-kilometer trail of the barricade from one end to the other, photographing each concrete defender in its natural habitat. At the beginning of the project, it felt like retracing a neat piece of history, by the end, fears of invasion didn’t feel so far in the past.