The darkish fragment can be extracted from the wall.

Note the eye sign shows a keyhole. Find the same keyhole on another side of the box.

To release the parts, you have to push the sliders in opposite directions simultaneously. Then turn over the box – the unlocked parts will fall down.

The men are showing where they pull the sliders.

Notice the men are pulling the rope.

After you have removed the lid from the towers puzzle, you will see movable sliders.

Rotate the outer disc so that its notch points to the lock symbol. Then you can take out this lid.

There is a lock sign near one of the towers.

While the discs are in the correct position, extract the key from the other side of the box.

Connect the towers by setting the discs as shown below. Version 1 (with 3 discs) Version 2 (with 2 discs)

4 towers were damaged and their original shapes are unknown. 2 of them could have the necessary shapes. Try to connect these towers by rotating the discs. Version 1 (with 3 discs) Version 2 (with 2 discs)

Find the towers depicted on the top of the box taking into account the shape of their flag, window and door.