This grand corner home within the Park Slope Historic District was designed by Lawrence B. Valk for Charles Pied. The corner home and the three buildings to the south were all designed in the same Romanesque Revival style. No. 21 is known as the Lillian Ward Mansion as it was once the home of Ward, a famous late 19th century singer. On the morning of December 16, 1960 two commercial airliners collided in the airspace over Staten Island. One of the pilots, attempting to land the plane in Prospect Park, came down instead at the corner of Sterling Place and 7th Avenue, directly in front of the Ward Mansion. All 128 people on both planes were killed, as well as six people on the ground. The debris scattered around the neighborhood and set more than 10 buildings on fire. A church on Sterling Place was completely destroyed while the building directly across from No. 21 had its cornice sheared off by the crashing plane. Somewhat surprisingly the mansion was left completely unharmed.