Most of the major monuments and memorials on the National Mall in Washington, D.C., are open 24 hours a day, 7 days a week. This includes iconic sites like the Lincoln Memorial, World War II Memorial, Korean War Veterans Memorial, and the Vietnam Veterans Memorial. Visiting at night is highly recommended as the structures are beautifully illuminated, offering a more serene and contemplative experience compared to the busy daytime hours. However, while the sites are physically accessible, National Park Service rangers are typically only on duty to answer questions from 9:30 AM to 10:00 PM daily. The Washington Monument is a notable exception; it requires a ticket for entry and follows specific operating hours, generally from 9:00 AM to 10:00 PM, with the last entry usually around 9:30 PM.