The ERO Concrete Recycling Robot recently won the IDSA IDEA contest, led by Omer Haciomeroglu, and was conceived as a solution more cost-effective than demolitions. Moreover, it would help to recycle construction materials.
That is how the ERO robot would help to suck and recycle the entire concrete structure of a building as it goes along. With the help of a water jet it cracks the concrete, sucks it and finally packs it to be reused in other prefabricated concrete structures. That way the metal structure is also ready to be melted and reused.
This is a great option for development, since it saves a lot of energy, and because it opens the door to recycling and reusing tons and tons of expensive construction materials after their first years of use.