In recent years, the evolution of urban environments, jointly with the progress of the
Information and Communication sector, have enabled the rapid adoption of new solutions that
contribute to the growth in popularity of Smart Cities. Currently, the majority of the world population
lives in cities encouraging different stakeholders within these innovative ecosystems to seek new
solutions guaranteeing the sustainability and efficiency of such complex environments. In this work,
it is discussed how the experimentation with IoT technologies and other data sources form the cities
can be utilized to co-create in the OrganiCity project, where key actors like citizens, researchers and
other stakeholders shape smart city services and applications in a collaborative fashion. Furthermore,
a novel architecture is proposed that enables this organic growth of the future cities, facilitating the
experimentation that tailors the adoption of new technologies and services for a better quality of life,
as well as agile and dynamic mechanisms for managing cities. In this work, the different components
and enablers of the OrganiCity platform are presented and discussed in detail and include, among
others, a portal to manage the experiment life cycle, an Urban Data Observatory to explore data assets,
and an annotations component to indicate quality of data, with a particular focus on the city-scale
opportunistic data collection service operating as an alternative to traditional communications.