Complex sentence: During Massachusetts Mutual's ownership of the Chrysler Building, the tower received two historic designations: the National Historic Landmark status, awarded in 1976, and and the New York City Landmark status, awarded in 1978 to the lobby and facade.
Split into simpler sentences: During Massachusetts Mutual's ownership of the Chrysler Building, the tower received two historic designations. The building was designated as a National Historic Landmark in 1976, and and as a New York City Landmark in 1978, although the city only landmarked the lobby and facade.