The exchange between Vienna and Sofia focuses on the environment, the fight against climate change, the transition to renewable energy sources, sustainable waste management and recycling, urban planning, mobility and smart city. One more link is the joint participation in the European Strategy for the Danube Region. Since 2021, experts from nine partner cities, including Sofia, have been learning how to better manage cities in the 21^st century in two consecutive master's courses at the FH Campus Wien.