The integration of civil unmanned aircraft systems (drones) into airspace has turned out to be a real challenge. Drones have difficulties in following many of the rules designed for manned aviation, because drones are plentiful and cheap, because they have no pilot on board, and because they are often flown at a very low altitude. This creates major issues relating to safety, traffic management, privacy, and law enforcement. To solve them, European regulatory bodies have come up with a new concept: U-space.    In this article, I focus on that particular concept. First, I explore several rules designed for manned aviation; second, I present several challenges posed thereto by drones; and third, I analyse how these challenges will be solved in U-space.  My analysis emphasizes that U-space is not merely a legal but also a technological concept, and it is as much a public as it is a private effort. I maintain that this interplay is necessary, since it is counterproductive to develop the concept without taking into account emerging technology and without close cooperation with the industry. My analysis also acknowledges that many U-space services are already available today. However, since many of such services are fragmentary and have only been demonstrated in a controlled environment, I argue that it will take much more effort to bring the concept to its full fruition.