Robins are masons when it comes to constructing their nests. This sturdy nest is unexpectedly heavy; all of the grasses, stems, and other materials are pasted together with mud. This nest was perched atop a circuit box on the side of the house. If you look at the next picture, you'll see why it was safer than it looked--it was mortared in place. A nice impression of the hinge (or something) remains.
The house finches return to the porch every year and raise several broods (new nest each time) in my hanging baskets. This year one pair scored a personal best by starting a nest within 10 minutes of my hanging the ferns from the hooks. I waited patiently while the finches hatched, nurtured, and fledged their offspring, then tried to revive my battered fern. I was not pleased to discover that a new nest was under construction in the other hanging basket, so I removed the nest--and discovered that this one had a special feature. It's lined with fur, I believe from a squirrel's belly.
A lightweight, attractive nest makes an interesting addition to a wreath or Christmas tree. I would not suggest using a robin's nest.