The United Nations (UN) 2030 Sustainable Development Agenda, signed in 2015 and backed-up with its seventeen Sustainable Development Goals (SDGs), mentions cities as key players for evolving actively towards more sustainability. This underpins that living in the cities of the urban age is increasingly becoming the focus of sustainability discussions, which is particularly reflected in SDG 11 “Making cities and human settlements inclusive, safe, resilient and sustainable”. As urban sustainability strategies are playing a key role for the development of cities, this article sheds light on four cities’ sustainability strategies. The case studies highlight shortcomings, in terms of integrated visions, clear targets, and indicators in existing urban (sustainability) strategies. The article discusses these issues in light of an analytical framework, and stresses challenges and opportunities that SDG implementation involves.