Complex sentence: During the last half of the 20th century the Emmerich Gallery located in the Fuller Building at 41 East 57th Street and in the 1970s also at 420 West Broadway in Manhattan was one of New York City's leading art galleries.
Split into simpler sentences: During the last half of the 20th century the Emmerich Gallery was located in the Fuller Building at 41 East 57th Street and in the 1970s also at 420 West Broadway in Manhattan. The gallery was one of New York City's leading art galleries.