Blame! Movie, Made in Abyss Recommendations
Both have that same mystery feeling of "what lies below in the deep depths" and the settings of the stories and surroundings are pretty similiar to each other.
If you liked Made In Abyss then you'll surely like Blame! too, no doubt :)
If you are looking for more exploration of giant, mysterious, and old structures with amazing landscapes, you should probably give the Blame! movie a try. Blame! also happens to have a main character that has an awesome laser beam that can shoot through anything, which is always a very deeply satisfying thing to see in my opinion.