Build an isometric voxel extension ...

Build an isometric voxel extension for the structure in image provided. Extend the building backwards to form a U-shaped courtyard. The new rear wings must perfectly match the gray stone brickwork, dark slate mansard roofs, window styles, and red banners from the image provided. Enclose the open back of the U-shape with a crumbling blocky stone wall and a heavy wooden gate. Inside the courtyard, add a stone-paved floor and two more glowing crystal spires on pedestals. Outside the gate, construct a weathered cobblestone path leading to a rustic stone well, surrounded by dark spruce or pine trees on muddy ground. Maintain the exact gothic architectural style, isometric perspective, and block scale of image provided.