In the global war on terrorism, cities worldwide have implemented a multiplicity of urban counterterrorism measures to protect buildings, public spaces, and citizens against terrorism. Since few previous studies have examined the historical development of urban counterterrorism measures in a concrete city, we examine the development of urban counterterrorism measures in Norway’s capital Oslo from 1993 to 2023. This chapter contributes with knowledge of the exogenous and endogenous factors that influence implementation of urban counterterrorism. Five different periods of urban counterterrorism are identified, which are associated with different potential targets and different forms of attack modus. During each period, new layers of urban security measures have been added while those already implemented persist. The conclusion is that there is a dissonance between the aims and realities of urban counterterrorism measures that impact the security and freedom of citizens. Future research should further investigate the impacts of urban counterterrorism on cities.