<P> The building was part of the later Rockefeller Center expansion (1960s--1970s) dubbed the "XYZ Buildings". Their plans were first drawn in 1963 by the Rockefeller family's architect, Wallace Harrison, of the architectural firm Harrison and Abramovitz . Their letters correspond to their height . 1251 Avenue of the Americas is the "X" Building as it is the tallest at 750 ft (229 m) and 54 stories, and was the first completed, in 1971 . The "Y" is 1221 Avenue of the Americas, which was the second tower completed (1973) and is the second in height (674 ft and 51 stories). The "Z" Building, the shortest and the youngest, is 1211 Avenue of the Americas with 45 stories (592 ft). 1251 is the second - tallest building in the whole of Rockefeller Center, after the Comcast Building . </P> <P> Despite being one of the 100 tallest buildings in the United States, 1251 Avenue of the Americas is almost impossible to see from more than just a few blocks away as it is flanked on all sides by buildings over 500 feet tall . The result is that even though 1251 Avenue of the Americas is approximately as tall as the tallest buildings in cities such as Boston or Minneapolis, it has almost no presence on the New York City skyline . </P> <P> In 1989, Exxon announced that it was moving its headquarters and around 300 employees from New York City to the Las Colinas area of Irving, Texas . Exxon sold the Exxon Building, its former headquarters, to a unit of Mitsui Real Estate Development Co. Ltd. in 1986 for $610 million . John Walsh, president of Exxon subsidiary Friendswood Development Company, stated that Exxon left New York because the costs were too high . Its New York offices moved to Brooklyn; it no longer retains a presence in Rockefeller Center . </P> <P> Inside, on the western end of 1251's atrium hangs an artist - authorized replica of a tapestry Pablo Picasso created for the ballet Mercure, the original of which hangs in the Musée National d'Art Moderne in Paris, France . It was created specifically for 1251, as per the plaque beneath it . </P>

1251 ave of the americas new york ny 10020