The concept is fantastical: Tall yet compact structures brimming with windows, and from those windows robots merrily delivering packages. Some are boxy towers, others fanciful hive-shapes. All are framed as a hedge against zoning laws, a way to put a high-density warehouse in the middle of a city, for fast delivery directly to customers. “Fulfillment centers are typically large-volume single-floor warehouse buildings used to temporarily store items prior to shipment to customers,” reads the patent, “Often, due to their large footprint, these buildings are located on the outskirts of cities where space is available to accommodate these large buildings. These locations are not convenience for deliveries into cities where an ever-increasing number of people live. Thus, there is a growing need and desire to locate fulfillment centers within cities, such as in downtown districts and densely populated parts of the cities.” It’s ambitious and clever, if not completely novel, but it poses some specific challenges in terms of urban infrastructure.