Introduction.-An Introduction to Ontologies and Ontology Engineering.-Ontologies for Interoperability.-Alignment and Viewpoints in Ontologies.-Ontologies and Multilingualism.-Part II: Ontologies in the Urban Domain.-Ontologies in the Geographic Information Sector.-Ontologies for Interconnecting Urban Models.-Call for LOD - Linking Scales and Providers through Digital Spatial Representations.-Ontology-Based Interoperability in Knowledge-Based Communication Systems.-Transformation of Urban Knowledge Sources to Ontologies.-Part III Case Studies.-Examples of Developing and Using Ontologies in Practice.-URMOPRO: An Example of an Urban Ontology for the Formalization of Morphological Processes.-OUR City Cohesion Policies: Practices of Ontologies For Urban Regeneration (OUR): The Case Of The Puglia Region.-An Ontology for Urban Mobility.-The Development of Thesauri by English Heritage.-Ontology and the Scottish Building Regulations.-Road System Ontology: Organisation and Feedback.-Impact of BIMs on Business Models in Construction Industry.-Lessons Learned and Current Challenges