Urban operations are currently of great concern to the defense community. J9, the Experimentation Directorate of USJFCOM, and the Joint Advanced Warfighting Project are currently conducting an experiment to investigate concepts for applying future technologies to joint urban operations. The first phase of the experiment focuses on employing future sensors to remotely monitor and understand enemy operations in a foreign city. Characteristics of the urban environment include high building density, a large civilian population, and a cultural environment. These characteristics pose significant challenges for simulation designers. This paper describes the modifications required to adapt the simulations supporting the experiment, JSAF and SLAMEM, to the urban environment. A landscape with a large number of buildings had to be automatically generated and represented in a space efficient manner. Large concentrations of vehicles and pedestrians had to be modeled moving realistically through the city. This behavior had to be automatically generated since it would be impossible to individually control 100K entities. Embedding cultural features within the database in the form of building functions and other building attributes allows the civilian entities to automatically plan their movements based on generic daily schedules. Sensors had to be modified to detect building properties. The density of both entities and structures made both movement and intervisibility calculations significantly more expensive requiring optimization combined with the application of large amounts of hardware. Computation and control was distributed between three CONUS sites and the High Performance Computing Center at Maui. Limiting and balancing simulation traffic was a major effort. Source squelching was enabled by a distributed data collection system developed to collect data locally on each simulation node while still allowing analysts to perform real time queries during the experiment.