The paper outlines results of feasibility experiments with new functions for a local version of the digital city, performed under a collective name ‘Engineering City Oulu’ (ECO). We investigated design and implementation options supporting engineering services in the digital city. The options were oriented towards local needs and potentials of the Oulu economic area. Many technologies can be used to support user interaction in digital city systems, such as 3-d imaging, on-line sensory data, culture-sensitive instruction, etc. We focused on supporting engineering - a fundamental activity of real city users. In the experiments we emphasised conditions for active participation of users (‘digital citizens’) in the community decision making. A broad classification of engineering support in digital cities is introduced followed by motivation of the feasibility studies. Then the requirements for an innovative digital city are discussed. The main feasibility results are then presented including a selection of basic engineering models and an outline of the experiments new software, applicable in digital cities.