This is hard to believe and we are definitely living in the future.  Who would have thought this would be possible a few decades ago:

Except for the required anchor points at both ends of the structure, the bridge consists exclusively of tensile elements and its connections and links are entirely realized by flying machines. Spanning 7.4 m between two scaffolding structures, the bridge consists of nine rope segments for a total rope length of about 120 m and is composed of different elements, such as knots, links, and braids. The rope used for these experiments is made out of Dyneema, a material with a low weight-to-strength ratio and thus suitable for aerial construction. Of little weight (7 g per meter), a 4 mm diameter rope can sustain 1300 kg.

The vehicles are equipped with a motorized spool that allows them to control the tension acting on the rope during deployment. A plastic tube guides the rope to the release point located between two propellers. The external forces and torques exerted on the quadrocopter by the rope during deployment are estimated and taken into account to achieve compliant flight behavior. The assembly of the bridge is performed by small custom quadrocopters and builds upon the Flying Machine Arena, a research and demonstration platform for aerial robotics. The arena is equipped with a motion capture system that provides vehicle position and attitude measurements. Algorithms are run on a computer and commands are then sent to the flying machines via a customized wireless infrastructure.

We hope you like the video!  What will they think of next?  Would you use drones for shipping items from Amazon because that is being discussed right now?

thanks to ethz.ch for the great info