As a part of their digital transformation, municipalities across Europe have taken initiatives to support Open Data platforms and provide services leveraging on data. This challenges the traditional business driven IT strategy promoted by several Enterprise Architecture methodologies, which are designed to operate within a single enterprise that has a complete overview of its data and ICT systems. We envisage scenarios where public and private collaborative networks provide value added services to its citizens by leveraging on data. In this paper, we propose an Enterprise Architecture Framework for Cities to support them maneuvre smartly within their data space to create value added services through a variety of collaborative networks or Virtual Enterprises that bridge organisational boundaries. The novel elements of this Enterprise Architecture Framework are a DataxChange, the Value-Added Services and Virtual Enterprise layers. This work has been conducted within the EU H2020 Smart City project +CityxChange.