the half-hour. The visitor center is open seven days a week from 9:00 a.m. to 5:00 p.m., except on Thanksgiving, Christmas, and New Year's Day. Park rangers offer interpretive talks and an audio tour is available for purchase to accompany the self-guided driving tour of the battlefield with eleven stops. Park Grounds are open daylight hours. There is a park entrance fee of $10.00 per person (age 17 or older; 16 and under FREE) or $20.00 per vehicle. The entrance fee is valid for three days. Pry House Field Hospital Museum The Pry House Field Hospital Museum is located in the house that served as Union Commander General George B. McClellan's headquarters during the battle. Exhibits focus on period medical care of the wounded, as well as information about the Pry House. The museum is sponsored by the National Museum of Civil War Medicine. Antietam Battlefield Illumination This memorial illumination was started in 1989 and continues to this day on the first Saturday in December. Every year, over a thousand volunteers place 23,000 luminaries in rows on the northern portion of the battlefield. The luminaries consist of a paper bag filled with sand and a candle, and represents a soldier that was killed, injured, or went missing during the Battle of Antietam. Additional battlefield preservation The Antietam National Battlefield was listed as one of America's Most Endangered Places in the years 1988, 1989, 1990, 1991, according to the National Trust for Historic Preservation. The Battlefield was added to the list in response to a "...flawed proposal to construct a shopping center and other buildings on battlefield land, the listing helped to galvanize support and action by local, state and federal agencies and non-profit organizations." By 2017, the Antietam National Battlefield was deemed a success story and was included alongside ten other sites that previously named to the Most Endangered and also became the focus of successful preservation efforts. The American Battlefield Trust and its federal, state, and local partners, including the Save Historic Antietam Foundation, have acquired and preserved of the overall battlefield through late 2021, including the "epicenter" tract, a 44.4-acre, previously privately owned parcel in the heart of the battlefield park between the Cornfield and the Dunker Church. The land, also known as the Wilson farm, was purchased by the Trust in 2015 for about $1 million. The preservation organization has since removed the postwar house and barn