Yes, the Lincoln Memorial is open to the public 24 hours a day, and visiting at night is often considered the best way to experience it. At night, the crowds are significantly smaller, and the monument is beautifully illuminated, with the statue of Abraham Lincoln glowing against the white Georgia marble. National Park Service Rangers are typically on duty from 9:30 AM to 10:00 PM to answer questions, but the site remains accessible even after they depart. Walking up the steps from the Reflecting Pool under the moonlight offers a solemn and powerful perspective that you simply can't get during the busy daytime hours. The area is generally well-lit and monitored by the U.S. Park Police, making it a safe and popular spot for late-night walks or photography. Just be mindful that while the memorial itself is open, nearby facilities like the bookstore and public restrooms within the lower level usually close by 10:00 PM.