This Georgian Revival mansion, constructed in 1919, was built for Thomas Frothingham and later sold to John Sloan, a prominent furniture retailer. It was designed by John Russell Pope, a leading designer of country houses for wealthy patrons early in the 20th century. He was later known for his monumental architecture in Washington, D.C., including the Jefferson Memorial. The mansion now houses the United States Golf Association Museum. Open Tuesday to Sunday 10 a.m. – 5 p.m.