The result of the Historical Ontology of Urban Space project is a strong international cooperation network for researchers dealing with and interested in the history of the city (average European city). During a series of workshops, problems connected with the changes that occurred in the city space from the late Middle Ages (from the 16th century) to the beginning of the 20th century along with permanent elements that we think can constitute the city were discussed. As a result, an ontology of urban space was created.