by Katherine O. Rizzo and Kim K. Egan (first published in the September 2022 Equiery)

Not only is Rosaryville State Park the most popular trail riding destination in Prince George’s County, according to the 2021 Equiery trails survey, it is also the sixth most popular park in all of Maryland. The 982-acre park is managed by Maryland DNR and holds approximately 16 miles of multi-use trails. Rosaryville is home to the Marlborough Horse Trials and also holds hunter paces and other activities throughout the year.

The entrance to the park is off ​Route 301/Crain Highway​ in Upper Marlboro. The park began charging an entrance fee as of July 1, 2022, via an automatic toll gate. On Monday through Friday the fee is $3 per vehicle for Maryland residents and $5 per vehicle for out-of-state residents. On weekends and holidays the fee is charged per person, not per vehicle. Visitors can pay the fee by debit card, credit card, or cash. All Maryland State Park passes are accepted as well.

The park is open from 8 am to sunset each day and there is plenty of trailer parking in the main area of the park. The main trails are the 1.5-mile Agriculture Heritage Trail, the 2-mile Grassland Bird Trail, the 9.75-mile Perimeter Trail, and the 3-mile Tilly Trail.

The Agriculture Heritage Trail combines history and nature on an easy down-and-back trail that alternates between following the road and paths through the park. You will see old barns, silos and other remnants of the former working farm along the way. There are a few interpretive panels displaying the history behind the park as well. The trailhead is located by the old Tobacco Barn.

The Grassland Bird Trail is a loop-trail popular with those interested in seeing wildlife, especially migratory birds and pollinators. The majority of the trail follows the edge of the fields where they touch the surrounding woods. The recently completed vegetated stormwater retention pond attracts several different species of birds. The trailhead for the Grassland Bird Trail is by the pavilions. Follow the orange trail markers.

DNR says the Perimeter Trail is the most popular loop-trail in Rosaryville. The trailhead is at the Fred Eskew Recreation Area (pavilion, playground, etc), and the trail is a single-track of moderate difficulty (on foot) with ample changes in elevation. This loop also leads to several of the trail networks that cross through the center of the park, including the Tilly Trail, which is a good option for those looking for a shorter loop from the Perimeter Trail.

Mount Airy Mansion
The park is on land once owned by the Calvert family which they used in the 17th and 18th centuries for hunting parties. In 1751, Benedict Swingate Calvert (1722-1788), an illegitimate son of Charles Calvert, 5th Lord Baltimore, inherited the land and began building Mount Airy Mansion on the foundation of the original hunting lodge.

By the 1770s, Benedict Calvert was a local politician and wealthy tobacco farmer who owned over 150 enslaved people and who also bred and trained racehorses at the Mount Airy property. In 1774, his daughter Eleanor married George Washington’s step-son, John Parke Custis, at the mansion, with George Washington in attendance.

Benedict’s wealth and status were deeply affected by the Revolutionary War, however, because his family connection to the Washingtons notwithstanding, Benedict was a royalist which meant he had to pay triple taxes on his property when the war was over. He bequeathed Mount Airy Mansion to his second son, Edward Henry Calvert (1766-1846), and it remained in Calvert hands until 1902.

In 1902, Mrs. Matilda R. Duvall purchased the property at auction and renamed it Dower House. She ran a country inn and exclusive restaurant there until a fire in 1931 burned it down. The ruins of the Dower House were purchased by Cissy Patterson, Countess Gizycki, who was a novelist and the publisher of the Washington Times-Herald, and who restored the mansion and entertained important political figures there during and after WWII. Patterson bequeathed her property to Ann Bowie Smith, a distant relative of the Calverts, who sold it to the State of Maryland in 1973. The state leased it to the Chambord Corporation in 1983 as the exclusive Mount Airy Plantation Restaurant and Country Inn until the early 1990s.

Matilda’s son Peter Duvall inherited the 341-parcel that surrounded the house itself. In 1976, Peter and his wife Esther D. Duvall deeded their parcel to the Maryland DNR, which then established Rosaryville State Park. Over the next several decades, smaller surrounding parcels, including the Mount Airy Mansion itself, were either purchased or donated to the park, and the land now covers almost all of the original Calvert family acreage.

For more information and trail maps, see