The Urban Environment has been developed through centuries as a complex machine to host human beings and their activities, excluding external factors disturbing anthropogenic activities. Part of this process consisted in excluding the so-called “nature” (except a few selected species) from cities. However, a new consciousness about the effects of anthropogenic activities on our planet and about the regulating properties of nature on the environment is bringing us to reconsider the introduction of nature in cities, rethinking our cities as environments built to host multispecies co-existence and collaboration.