Create a visual representation of an autism center situated on a scenic hill surrounded by lush pine trees. The design features a four-story building on the left, specifically designed as sleeping units for patients. This section should appear serene and comforting, emphasizing the restful atmosphere, and be constructed from concrete for a sturdy yet inviting look. In the center, depict an elongated two-story activities building made of concrete that connects to the first two floors of the sleeping unit, showcasing spaces for various therapeutic and recreational activities. To the right, illustrate a cafeteria building that juts out perpendicularly, featuring large windows to highlight its inviting atmosphere and view, also constructed from concrete. As you move upward, show the building gradually becoming more accessible to the public, with ample windows and openings that differentiate the spaces. At the rear, design a welcoming entrance that seamlessly integrates with the overall block, creating a cohesive and inviting entrance to the entire project. Focus on creating a harmonious blend of functionality and tranquility, reflecting the purpose of the center.