Johanna Mårtensson's bread city is an examination of what happens to modern cities after human inhabitation ends, and the structures are left to the will of nature. Of modern metropolises, Johanna thought, "Within 500 years all buildings would be half-fallen or fallen, perfect homes for animals and plants. The forest would soon grow in cities. Afterhand, buildings as well as pollutions would be taken care of by bacteria and micro-organisms. A UFO that came here in a couple of hundred thousand years would not see many signs that a gang of primates once thought that they were the lords of the planet."
To demonstrate the natural state of submission to the elements, Mårtensson bult a bread city, which she photographed over a period of six months to observe its decay and the "creation of a new process," through which the city would belong not to humans, but to micro-organisms.