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Rosaryville is a 982 acre day-use park and the location of the historic Mount Airy Mansion. Miles of trails for hiking, biking and equestrians are available for day use. To gain access to Rosaryville State Park, make a right turn into the entrance just south of Osborne Road while traveling south on U.S. 301.
Sunrise to Sunset
(Note: Many places fill to capacity on busy, nice weather days, especially holiday weekends. Please call ahead or visit the official website to get the most up-to-date information before visiting.)
Honor system chargeable at all times. Open year-round from sunrise to sunet. Full service use of the park and picnic pavilions is May through October, Friday through Sunday. Reduced service access to the park is available at all other times (gate is closed after the first parking lot).
Beautiful Mount Airy Mansion is located in the heart of Upper Marlboro's hunt country and is one of the oldest Maryland mansions connected to the Calvert family, the Lords Proprietor of colonial Maryland. Some historians speculate that parts of the building may date from the 1670s and served as a hunting lodge for the Lords Baltimore.
However, a 1752 edition of the Maryland Gazette makes clear that whatever was there burned to the ground in that year. Benedict Swingate Calvert, the property owner at the time, probably built the east wing of the present structure shortly thereafter to replace the lost structure.
Over the years, as the property descended through the Calvert family, the structure was enlarged to its modern proportions.