One of the most common objections to large-scale urban farming is the cost. Indeed, when new buildings have to be purpose-built, it can be prohibitively expensive. That’s why this concept from designer Daekwon Park is especially brilliant: it uses existing skyscrapers to support modular vertical farm structures. There are a few different types of modules which all perform specific functions; they would be arranged on the outside of the buildings to provide maximum growing area. Although this particular idea is far from being possible at the moment, it goes to show that there is a wide variety of ideas for urban farms out there.