A rocky cyberpunk cave entrance labeled "SECTOR 3", carved directly into a cliff wall. The portal should have a rugged, natural stone arch surrounded by rough rock formations, with subtle neon orange lights embedded into the stone. The environment is inside a dimly lit cave, illuminated by scattered cyberpunk light elements like glowing wires, flickering tubes, and digital panels partially overgrown by moss. The entrance should look imposing and ancient, but slightly futuristic due to the lighting and subtle tech enhancements. Focus on hard rock shapes and asymmetry.