The 3 natural bridges and Houping giant doline

Thanks for your reply. I'd ask for more informations : a video clip from youtube of Wulong, and I saw the glass elevator from top to bottom of the mountains. I'd ask where this elevator is located at Tienkerng or 3 Natural Bridges. And why the above details saying that tourists will visit Houping Doline before 3 Natural Bridges. How about the condition (the paths+stairs) to walk among these 2 places? I want to walk slowly to view these beautiful landscapes.
If I want to visit these 2 places, how long do I spend time (walk) inside?