A huge lava citadel built on top of...

A huge lava citadel built on top of a volcanic hill. The structure is made from blackstone, basalt, and nether bricks. It has multiple full above-ground levels connected by staircases and towers. Each level contains separate closed rooms and corridors of different sizes. Some rooms are small and narrow, others are large arena-style halls. The design should be symmetrical, complete, and fully solid without damage or holes. Add lava outside the structure for atmosphere, but keep the building intact.