There are quite a lot of different buildings and observation platforms in the Czech Republic, the entrance to which is free. Here, for example, is such an observation deck called Dubrovka.
Almost literally made of shit and sticks. Okay, there is no shit, but for the most part it is built of sticks. The sticks are combined with metal anchor bolts, and the upper part of the structure is pulled together with a metal structure, like a cap.
During its design, a large number of different options were proposed, in the end they settled on this.
The total height of the building is more than 20 meters, and you can climb it by a spiral staircase inside the structure.
In this case, the spiral staircase does not touch the ground, but is suspended from the upper part of the structure. Therefore, it dangles during ascent and descent, as well as in the wind.
And to be honest, at one time this design told my eyes, because I was developing software, the previous version of which was used to calculate the static loads of this design. Well, we used this project as a test for the new version.