The mild climate on Gotland makes it possible to grow a lot of trees from warmer countries and climates. Here are some that I found interesting to see: (because I don't normally see them)
In the botanic garden in Visby - a zelkova tree!
Also in the botanic garden - a japanese magnolia, the seeds.
By the city wall: mulberry!
Over my head on some cafe: some kind of walnut...
In the forest: clematis vitalba.
Now I am getting less certain of the species, but this must be a laburnum with seeds.
And on these two last pictures I don't know at all what it is! Maybe somebody can tell me.