Minecraft ideas of what to build?

Okay, I've been playing minecraft for ages, I've made a massive house, an indoor swimming pool, an indoor stable, a train station(which has minecarts) , a hotel, a fun world with rollercoasters, and a ship. I really don't know what else to make, and I love making things and want to create a YouTube channel for my minecraft world once I've made more, but I just have completely ran out of ideas?

I would recommend working on an entire city, complete with suburbs, parks, defining landmarks and features, one or two especially tall skyscrapers, roads and highways, etc.

It will take an extremely long time to plan and build, but you are out of ideas, so you are in no hurry, I suppose. Also, after completion, you will get massive satisfaction, and you can show it off on your YouTube.

You could make an underground city. Like a huge labyrinth deep under the surface. It's a lot of digging, but it sounds awesome.