Also known as Las Setas de la Encarnación (Incarnation's mushrooms, since the structure is located in Plaza de la Encarnación), this is a wooden structure that is rather large, and is perhaps the largest wooden structure in the world. You can actually climb this: there is a path that you can venture into once you ride the lift that goes to the top. And this path allows you to see a very interesting panorama of Seville.
The structure is very visually arresting, and I must say, I enjoyed my visit. There are plenty of people congregating at the bottom, like children playing, skaters doing their thing, and many other people, just chilling. If you're in Seville, you should definitely check this out.