Inspired by the Tower of Babel from the Book of Genesis, artist Bob Vershueren built a huge birdhouse in Annecy, France. Implantations, as he calls it, was exhibited at the Jardin de l’Europe in 2017.
It's not the most efficient of designs. But it looks more organic this way--as though families of birds have gradually built houses on top of each other as time passed on. You can see more photos at Colossal.
Photo: Annecy Paysages