I have one! Build a big temple where the whole floor is a mirror (basically just flip the build upside down and put glass between them) for the roof do a big dome (half sphere) and on the inside on the roof do sun and moon with stars. In the middle you can build a big tree.
Just an idea
There are a lot of good builders on here to take inspiration from, it's how I get my inspiration sometimes by just asking to see what they're working on at the time and getting some creative juices flowing.
Good luck on your adventures and I can't wait to see your build!