1 William Street is an office building in the Financial District of Lower Manhattan in New York City. The building was erected in 1906–1907 and was designed by Francis H. Kimball in conjunction with Julian Clarence Levi. It was created for the Seligmans, a prominent German Jewish family who founded an investment bank called J. & W. Seligman. From 192…1 William Street is an office building in the Financial District of Lower Manhattan in New York City. The building was erected in 1906–1907 and was designed by Francis H. Kimball in conjunction with Julian Clarence Levi. It was created for the Seligmans, a prominent German Jewish family who founded an investment bank called J. & W. Seligman. From 1929 to 1980, the building was the headquarters of investment bank Lehman Brothers, and was subsequently bought by Banca Commerciale Italiana.