Create a brutalist abstract artwork featuring a geometric fortress with harsh lines and minimal color. Use a predominantly monochromatic palette with bold, geometric shapes and sharp angles to evoke a sense of strength and ruggedness. Incorporate subtle texture details, such as concrete or stone textures, to add depth and visual interest. Capture the scene from a low-angle perspective, with a shallow depth of field to emphasize the fortress's imposing presence. Apply a subtle HDR effect to enhance the sense of contrast and drama. (Image type: Digital art; Artistic style: Brutalist; Medium: Digital illustration; Camera settings: f/5.6, 1/100s, 50mm lens; Lighting setup: Harsh, with bold shadows; Background and foreground details: Geometric fortress with minimal color; Focus points: Fortress's structure and harsh lines.)