Gaudí’s designs for the Sagrada Família church in Barcelona, Spain incorporate themes of nature in many ways. The columns look like trees, so that it feels like you are standing in a forest while in the church’s nave. (They also remind me of celery stalks a bit.) It gives you the same feeling of peace as if you were really surrounded by trees, with the light filtering down to the forest floor.
For more about the architectural details of these columns, check out the church’s blog.
You can find more trees at the original Lens-Artist challenge.