Pictured: my spawn base
The enchanting room is a work-in-progress
The underground tunnel
My underground base
My OG nether base, which I originally lost because I built it too far away from the initial portal which I broke
Interior
My other nether base, which I built around the initial portal this time
I like those circular cave like the one in the first photo. One of my mob grinders routes into a cave like that. One of the walls is made of tinted glass so I can see the spawner.
Funny thing is it naturally generated like that