Known also as the Hilleary-Magruder House, this historic residence was constructed in 1742 by William Hilleary and is the oldest house in Bladensburg. It’s also the only 18th-century stone, gambrel-roofed house in Prince George’s County. The house was purchased from Hilleary by Scottish tobacco merchant Richard Henderson in 1763. Henderson had connections to George Washington, who dined there on May 9, 1787. According to the historical marker, he fell ill with a bad headache and an upset stomach. The house was sold to Dr. David Ross in 1793 and served…