CO2NSTRUCT is a pavilion for the 2025 Rotterdam World Expo. The main theme of the expo will be deltas in transition. There is a strong emphasis on sustainability and changing economic models. Another issue that needs to be addressed is the use after the expo. All too often these so-called mega events leave the cities organizing them with a lot of useless real estate. This makes the after expo use one of the focus points of the pavilion. This is addressed by the creation of a program related to urban farming and biomass creation, in this case, a park/plantation. This is where the second part of the concept ties in. The call from expo for change in the economic framework, is addressed by constructing the building along the principles of the biological cycle of the circular economic framework, as proposed by Ellen MacArthur. This part of the project consists of a series of small exhibitions all related to the circular economic framework. Their purpose is to educate visitors on this topic. After the expo not all of these exhibitions will be required anymore, and so will be removed. However, the resources obtained by the removal are to be used within the project. The urban farm that is part of the exhibit will be expanded. It will take the place of all the removed functions. So this pavilion can make a contribution to the surrounding area even after the expo is over.