I've just done a lot of Google to find a function that does this already, no luck.
1. I need to get all registered post types.
2. Loop through them (displaying them as a title)
3. For each post type get all buil-in taxonomy for that post type
4. Loop through each taxonomy as an item under the title
I don't mind if someone does not write the code. I just need to know the WordPress functions I should use. I tried various approaches but there are always taxonomies missing from the list or other issues.