2. There was no Lexington Avenue or Madison Avenue

Commissioner's Plan 1811-Map-NYC-Library of Congress-005

Lexington Avenue and Madison Avenue weren’t included in the Commissioner’s Plan, but emerged in the mid 1800s. Laywer Samuel Ruggles, who developed Gramercy Park, wanted to add Lexington Avenue between the already-existing Third and Park Avenues (Fourth Avenue in the grid) and Madison Avenue to increase the value of his land on Manhattan’s East Side.