Arbores Laetae - or Joyful Trees - is an installation at the Liverpool Biennial by architects/designers/artists Diller Scofido + Renfro, a kind of modern arboretum in which you not only move around the trees, but the trees dance around you. They've planted 17 hornbeams on a brownfield site close to Liverpool Cathedral; three trees revolve slowly around, changing shapes and shadows as they move.
Richard Scofidio, who founded the company as an architectural practice with Elizabeth Diller back in 1979,
told the BBC: "I found that it’s both beautiful, wonderful and a little bit frightening. Trees in poems are beautiful objects, but they are also things that tap on your window at night and in many fairy stories are quite evil and dangerous."