The new era of “big data” requires going past the current conventional methods for gathering traffic information that until now depend either on fixed-area sensors or GPS devices. Unmanned Aerial Systems (UAS) or just "drones" have been proposed as a modern tool of the Intelligent Transportation Systems infrastructure. The main scope of this paper is to examine the potential of drones in acquiring detailed traffic related information by describing a first-of-its-kind experiment, nicknamed pNEUMA , aiming to create the most complete urban dataset to study congestion. Specifically, a swarm of 10 drones flew over the city of Athens for more than 2 hours for 5 days to record traffic streams in a clogged zone of a 1.3km2 region. Detailed trajectory data is collected for more than half a million vehicles (cars, buses, taxis, powered two wheelers, medium and heavy vehicles). Preliminary results are presented and future research directions for researchers that many are beyond the interests and expertise of the authors are discussed.