The third day of the RRAU congress 16-18 April 2018 consisted of a city walk. On behalf of the RRAU congress, Maarten Vieveen (Research Centre NoorderRuimte) and Bart de Boer (BLG - Special Locations Groningen) provided a tour through the Der Aa-church. Summary: The Der Aa-church is a listed Gothic church building in the inner city of Groningen and is used for commercial and cultural events. Complaints about the indoor climate and the energy costs resulted in the assembly of a team to develop an integral design to improve thermal comfort and energy efficiency while historical qualities are preserved. During the tour, the history of the church was briefly summarized as well as how actors with various backgrounds currently weight divers interventions to develop a tailor made energy solutions for the Der Aa-church.